Extraction of cesium and strontium ions from nuclear waste

ABSTRACT

Methods and agents for extracting cesium and strontium ions from aqueous solutions, including aqueous fission product waste solutions, are disclosed using substituted metal dicarbollide ions containing one or more chemical groups that increase solubility of the substituted metal dicarbollide ion in non-nitrated, non-chlorinated solvents, or using metal dicarbollide ion-substituted silicones.

FIELD OF THE INVENTION

The present invention relates to radionuclide extraction agents andmethods for extracting radionuclides from nuclear waste. Moreparticularly, the invention relates to substituted metal dicarbollideion complexes and their use as transfer agents for extracting cesium andstrontium ions from aqueous nuclear waste.

BACKGROUND OF THE INVENTION

Nearly 500 isotopes are produced in nuclear reactors by fission andirradiation processes. Current options for dealing with high-levelwastes resulting from operation of fission reactors (e.g., nuclear powergeneration) include separation of long-lived uranium and plutonium fromother high-level wastes using some form of the PUREX(PlutoniumURaniumEXtraction) Process. The volume of the aqueous effluentfrom the PUREX process containing the remainder of the high-levelwastes, usually referred to as fission products, must then be reduced,and the residue solidified and eventually buried in a suitablerepository. The high-level fission products that remain in the aqueousphase subsequent to the PUREX process include ¹³⁷ Cs⁺ and ⁹⁰ Sr⁺². Theseradionuclides have potential commercial value and/or are problematic insubsequent disposal schemes. It has been estimated that 30 years afterreactor discharge, ¹³⁷ Cs⁺ and ⁹⁰ Sr⁺² account for 98% of the thermalenergy and 97% of the penetrating radiation in high-level waste, anddominate the design restrictions of waste repositories. Removal of thosetwo nuclides would have the same effect as aging the waste hundreds ofyears. Fission-product cesium in freshly discharged spent fuel consistsof the stable isotope ¹³³ Cs and the radioactive isotopes ¹³⁴ Cs(t_(1/2) =2.1 years), ¹³⁵ Cs (t_(1/2) =2.3×10⁶ years), ¹³⁶ Cs (t_(1/2)=13 days) and ¹³⁷ Cs (t_(1/2) =30.0 years), with ¹³⁷ Cs accounting forabout 43% of the total cesium. Fission-product strontium in freshlydischarged spent fuel consists of the stable isotope ⁸⁸ Sr and theradioactive isotopes ⁸⁹ Sr (t_(1/2) =50.5 days), ⁹⁰ Sr (t_(1/2) =29.1years) and ⁹¹ Sr (t_(1/2) =9.5 hours), with ⁹⁰ Sr accounting for about60% of the total strontium.

Various systems have been explored for the large-scale separation of ¹³⁷Cs⁺ and ⁹⁰ Sr⁺² from aqueous wastes including: (1) adsorption followedby precipitation, and (2) extraction. The present invention is directedto extraction agents and processes.

The extraction of rubidium and cesium ions into nitrobenzene usingaqueous solutions of tetraphenylborate was reported in 1956, in a thesisby a student at MIT. A few years later, government reports suggestedextraction as a viable technique for the removal of cesium ion fromnuclear fission waste. See, Smith et at., USAEC HW-76222 (1963) (citedin J. Inorg. Nucl. Chem., 30:611 (1968); Bray et at., USAEC HW-76222(1963), and Richardson, USAEC HW-75447 (1963).

In the late 1960's and early 1970's, several researchers studied theextraction of alkali metal ions and alkaline earth metal ions fromradioactive waste using a variety of agents, including dipicrylamine,pierate, tetraphenylborate, catechol, and catechol derivatives. Theextraction of cesium and other ions into various polar organic solvents,such as isoamyl alcohol, nitrobenzene, nitromethane, nitroethane,methylisobutyl ketone, and tdbutylphosphate was also reported.

The driving force for the extraction of cations from the aqueous phaseinto the organic phase is thought to be relief of the disruption ofhydrogen bonding in the water "structure" caused by the presence oflarge, non-hydrated or partially hydrated, cations of low charge (e.g.,Cs⁺). The selectivity and efficiency of extraction from the aqueousphase to the nitrobenzene phase is lower for alkaline earth ions (e.g.,Sr⁺²), than for alkali metal ions. Thus, the proposed order ofextractability is Ca⁺² <Sr⁺² <Li⁺ <Na⁺ <NH₄ ⁺ <K⁺ <Rb⁺ <Cs⁺.

All of the anionic phase transfer agents discussed above decomposed,existed in more than one form in relatively strong nitric acid media, orin some other way were less than satisfactory. For example, in stronglyacidic and radioactive extraction environments, tetraphenylborate iondecomposes to carcinogenic benzene, which can complicate subsequentprocessing.

During the early 1970's, it was reported that some polyhedral boranescould be separated from aqueous systems containing other ions by etherextraction. Extractability was shown to increase with the size of thepolyhedron, e.g., B₃ H₈ ⁻ <B₉ H₁₄ ⁻ <B₁₁ CH₁₂ ⁻ <Co(B₉ C₂ H₁₁)⁻² (cobaltdicarbollide ion).

The first transition metal dicarbollide ion complex (e.g., irondicarbollide, Fe(B₉ C₂ H₁₁)₂ ⁻) was reported by Hawthorne, et al. in1965. Previously, Hawthorne et al. had reported the degraffation ofcarborane (B₁₀ C₂ H₁₂) to dicarbadodecahydroundecaborate (-1) ion (B₉ C₂H₁₂ ⁻), the precursor of dicarbollide ion (B₉ C₂ H₁₁ ⁻²).

The 1,2-dicarbollide ion (1,2-B₉ C₂ H₁₁)⁻² and a transition metalbis-dicarbollide ion complex M(B₉ C₂ H₁₁)₂ ⁻, is sometimes referred toas a metal dicarbollide ion (or metal dicarbollide complex).

The numbering system for the atoms in the cage structures of isomericdicarbollide ions and bis-dicarbollide transition metal complexes inmost of the references cited is the "old system" in which the carbonatoms occupy positions 1 and 2 or positions 1 and 7, and the transitionmetal atom occupies position 3. To avoid confusion with the bulk of thepertinent references, the old numbering system is used herein.

To date, several metal dicarbollide ions have been made, including iron.dicarbollide ion, chromium dicarbollide ion, cobalt dicarbollide ion,and nickel dicarbollide ion. The chemistry of these complexes and someof their derivatives has been reviewed several times. See generally,Callahan and Hawthorne, "Ten years of metallocarboranes," Adv.Organomet. Chem. 14:145-86 (1976).

Although the sodium salt of cobalt dicarbollide is a strong electrolyte,the fact that it can be extracted into ether from aqueous solution ledto extensive studies of cobalt dicarbollide ion as a phase-transferagent, including examination of its use as an extraction agent forradionuclides. The following is a representative list of some of thepatents and other references that have been published about this topic:

Czech Patent No. 153933 (Ralsetal.) and J. Inorg. Nucl. Chem.38(7):1376-8 (1976) describe the extraction of radionuclides fromaqueous solutions using cobalt dicarbollide ion, and reported that,because of the solubility of cesium cobalt dicarbollide in variouswater-immiscible solvents and the distribution ratios of the cobaltdicarbollide ion in the organic phase relative to the aqueous phase,only polar solvents like nitrobenzene and some chlorinated solvents wereviable extraction media.

Scasnar and Koprda, in Radiochem. Radioanal. Lett. 34(1):23-8 (1978),reported the extraction of 137Cs⁺ into nitrobenzene in approximately 99%yield using the protonated form (conjugate acid) of unsubstituted cobaltdicarbollide ion. Subsequent to extraction, aqueous acids (>2M)effectively strip the Cs⁺ ion from the nitrobenzene phase.

Sr⁺² ion can be similarly extracted, but requires the addition of apolyethylene glycol (e.g. PEG-400) or p-nonylphenyl-nonaethylene glycol(e.g., Slovafol-909). Czech Patent No. 153933 (Raiset al.) and Collect.Czech. Chem. Commun. (Rais et al.) 44(1):157-66 (1979) describe theextraction of Sr⁺² from aqueous solvents using metal dicarbollide ionand polyethylene glycol. It is believed that the polyethylene glycolforms a complex with Sr⁺² through the oxygen atoms of PEG. Thehydrocarbon part of PEG is directed outward, making the complex morehydrophobic than the bare ion and thus more easily extracted into anorganic solvent.

In general, for the two-phase water-nitrobenzene extraction system,radionuclide extraction selectivity and efficiency does not depend onthe cobalt dicarbollide derivative employed. However, although thestability of unsubstituted cobalt dicarbollide ion in nitrobenzenetoward HNO₃ decreases markedly above 2M HNO₃, the dibromo- derivative isquite stable to 5M HNO₃. Selucky et al., in Ustav Jad. Vyzk. [Rep.], UJV5069 (1979), reported that both chlorination and bromination of boronatoms in the dicarbollide ion cage increases the stability of cobaltdicarbollide ion. Electrophilic substitution on boron atoms of thedicarbollide ion cage was reported as early as 1968 by Hawthorne andco-workers. In the mid-1970's, researchers in Czechoslovakia describedthe dibromination of cobalt dicarbollide complexes in 20% mixtures ofbromoform in nitrobenzene, and hydroxylation in chloroform or carbontetrachloride-saturated aqueous solution under radiation conditions.Direct bromination with bromine in methanol produced the 8,8'-dibromoderivative.

Matel et al. (Radiochem. Radioanal. Lett. 46(1-2):(1-6) (1981)attributed the improved chemical and radiation stability of thebrominated products to blockage of the reaction centers, and Coursel etal. (Can. J. Chem. 64(9):1752-7 (1986)) determined the regions ofgreatest electron density (boron atoms in the 8 position).

Czech Patent No. 242501 describes the 8,8'-dichlorination oftransition-metal dicarbollide complexes, including Co(III), Fe(III) andNi(III). Subsequently, Matel et al., reported in Polyhedron 1(6):511-19(1982), the chlorination and bromination of cobalt dicarbollide byelemental halogen in alcohols, and γ-induced halogenation by bromoform,chloroform or carbon tetrachloride in polar solvents. Halogenation wasreported to proceed alternatively in both cages yielding, successively,8-; 8,8'-; 8,9,8'-, 8,9,8',9'-, 8,9,12,8',9'- and8,9,12,8',9',12'-halogen derivatives.

Czech Patent No. 224890 (Rais et al.) reports the preparation of thehexachloro- derivative of cobalt dicarbollide ion, using elementalchlorine in acetic acid, on the 14 kg scale.

Extraction studies similar to those previously done using unsubstitutedcobalt dicarbollide ion were repeated using various halogenatedderivatives. For example, Czech Patent No. 224890 reports the extractionof Sr⁺² using the hexachloro-derivative, and Czech Patent Nos. 219525(Kyrs et at.) and 224993 (Macasek et al.) report the separation of Cs⁺and Rb⁺ ion using the dibromo- derivative.

Scasnar et al., in Radiochem. Radioanal. Lett. 50(6):333-43 (1982)reported a chromatographlc procedure for separating Cs⁺ ions from afission product mixture, using KEL-F (poly-trifluorochloroethylene) assolid support for cobalt dicarbollide ion or a chlorinated derivative innitrebenzene.

Selucky et al., in Radiochem. Radioanal. Lett. 38(4):297-302 (1979),described the development of procedures for the initial separation ofCs⁺ ion with 0.01M cobalt dicarbollide ion followed by extraction ofSr⁺² ion with a "hydrophobizing" agent (PEG). The most recent EasternEuropean work centers around fine tuning the extractions by solventvariations and/or by the addition of "synergetic" phase transfer agents.Thus, Selecky et al., in J. Radioanal. Nucl. Chem., 148(2):227-33 (1991)reported the extraction of fission products from nitric acid media using1,2-dichloroethane solutions of the hexabromo- derivative of cobaltdicarbollide ion. Babain et al., Radiokhimiya, 35(2):81-5 (1993),proposed diethyleneglycol-bis-(tetrafluoropropyl) ether as analternative solvent to nitrobenzene for extraction of Cs⁺ ion and Sr⁺²ion with chlorinated cobalt dicarbollide ion and Slovafol-909.Ivanovetal., Sib. Khim. Zh., (4):78-81 (1991), reported thattoluene/1-octanol and toluene/butyl acetate mixtures may be capable ofextracting Cs⁺ with very little dependence of the extraction efficiencyon solvent composition.

Tran et at., in Nucleon (2):6-9 (1993) reported the separation of Sr⁺²from Ca⁺² using an organic phase that contained 0.11M lithium cobaltdicarbollide and 1.7% Slovafol-909 in a solution of 40% carbontetrachloride/60% nitrobenzene. Their studies suggested that theefficiency of alkaline earth extraction increased with the number ofethylene oxide units in the range 2 through 8.

Zakharldn et al., Plast. Massy (11):61-3 (1990) reported thecrosslinking of polystyrene using cobalt dicarbollide ion, and proposedit as a sorbant for separation of fission products.

El Said et at., J. Radionanal. Nucl. Chem. 163(1):113-21 (1992)described an "Emulsion Liquid Membrane" system ofdi-2-ethylhexylphosphoric acid, n-alkane, dipicrylamine and cobaltdicarbollide ion in nitrobenzene stabilized with surfactant (SPAN80/85), and its use to separate radioactive Cs⁺ ion, Sr⁺² ion, Ce⁺³ ionand Eu⁺³ ion from acidic nitrate solution.

The field of fission products extraction was reviewed by Schulz et at.,in Sep. Sci. Technol. 22(2-3):191-214 (1987). See, also, Rais et al.,Nucleon 1:17 (1992), and Nukleon (4): 13-16 (1987).

Other agents and methods for extracting cesium and strontium fromaqueous nuclear waste are known and/or are being studied. For example,calixarenes have been studied as alkali metal ion complexing agents, andin the extraction of cesium ions from aqueous waste. Their subsequentdecomposition has also been studied.

Similarly, crown ethers are well known complexing agents for metal ionsand can be tailored to "fit" ions of different sizes. Both Cs⁺ and Sr⁺²have been extracted from aqueous systems using crown ethers. Crown etherterminated polysiloxanes in supported liquid membranes have been studiedwith regard to potassium ion transport. Alkali metal ion transportacross polymer membranes has also been studied.

To date, the known technologies for removing high-level fission products(specifically, ¹³⁷ Cs⁺ and ⁹⁰ Sr⁺² ions) from the strongly acidicaqueous effluent generated in most reprocessing procedures have used (1)solvent and complexing agent-intensive zeolite adsorption; (2)environmentally unfriendly solvents such as nitrebenzene and chlorinatedsolvents as the immiscible organic phase; or (3) agents, such ascalixarenes and crown ethers, that tend to be capable of efficientlyseparating only one of the two fission products of interest. Calixarenesand crown ethers both suffer from the drawback that, because of thestrong bonding interaction between metal ions and the oxygen atoms ofthe complexes, stripping the metal ions from the complexes is oftendifficult or impossible without destroying the complexes.

What is needed is a system capable of selectively and efficientlyextracting both ¹³⁷ Cs⁺ and ⁹⁰ Sr⁺² from high-level fission productwaste in a single, integrated process that avoids nitrebenzene,chlorinated solvents, and other drawbacks encountered with known fissionproduct extraction processes.

SUMMARY OF THE INVENTION

The present invention provides novel extraction agents and processes forselectively extracting cesium and strontium ions, and is particularlyuseful for extracting .cesium and strontium ions-including ¹³⁷ Cs⁺ and⁹⁰ Sr⁺² --from aqueous fission product waste. Extraction is accomplishedwithout using nitrebenzene, chlorinated solvents, or other highly toxic,hazardous solvents. Indeed, in one embodiment of the invention, nononaqueous phase is used at all. In other embodiments, kerosene, xylene,perfluorinated hydrocarbons, silicone oil, or similar materials areused.

According to the present invention, the new extraction agents comprisesubstituted metal dicarbollide ions having chemical moieties capable ofincreasing the solubility of the ions in water immiscible, non-nitratedand non-chlorinated solvents, and modified silicone oils or elastomersin which at least one substituted metal dicarbollide ion is chemicallybound to a silicone (organosiloxane) backbone.

Depending on the identity of the chemical moieties bound to the metaldicarbollide ion, the extraction agents are soluble in organic solvents,fluorinated hydrocarbons, silicone oils, or similar materials.

The present invention also provides new methods for extracting Cs⁺ andSr⁺² ions from aqueous solutions, using the extraction agents describedherein, and is particularly useful for extracting ¹³⁷ Cs⁺ and ⁹⁰ Sr⁺²ions from aqueous nuclear waste.

In one embodiment, extraction of cesium ions from an aqueous phase orsolution is facilitated by interaction with substituted metaldicarbollide ions contained in a nonaqueous phase. Once extracted intothe nonaqueous phase, the cesium ions are stripped therefrom bytreatment with mineral acid. Polyethylene glycol, or a similar compound,is then added to the aqueous phase, and strontium ions are extracted byinteraction with the substituted metal dicarbollide ions within thenonaqueous phase. Once extracted, the strontium ions can also bestripped from the nonaqueous phase by treatment with mineral acid.

In another embodiment, cesium and strontium ions are extracted fromaqueous solution by passage through a semipermeable membrane into anaqueous solution of mineral acid. No nonaqueous phase is used. Thesemipermeable membrane comprises a silicone elastomer containing pendantmetal dicarbollide ions bound thereto, or, a microporous polymer filmwhich has been impregnated with substituted metal dicarbollide ions. Themetal dicarbollide ions within the membrane facilitate extraction ofcesium and strontium ions into the aqueous acid solution.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other advantages of this invention will becomemore readily appreciated by reference to the following detaileddescription and accompanying drawings, wherein:

FIG. 1 is a schematic representation of a two compartment extractionapparatus of the invention in which the compartments are separated by asemipermeable membrane;

FIG. 2 is a schematic representation of an H-cell apparatus suitable foruse in the invention having a metal dicarbollide-substituted siliconeoil immobilized on a polymer film;

FIG. 3 is a schematic representation of a first embodiment of acontinuous extraction process of the invention; and

FIG. 4 is a schematic representation of a second embodiment of acontinuous extraction process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel extraction agents and processes forseparating cesium (Cs⁺) and strontium (Sr⁺²) ions from aqueoussolutions, and is particularly useful in extracting cesium and strontiumions (including ¹³⁷ Cs⁺ and ⁹⁰ Sr²⁺) from aqueous nuclear waste, withoutusing nitrobenzene or chlorinated solvents as the water immiscibleorganic phase.

The extraction agents of the present invention comprise substitutedmetal dicarbollide ion complexes having at least one chemical moietycapable of increasing the solubility of the complex in water immiscible,non-nitrated and non-chlorinated solvents. Each such chemical moiety isbound to a boron or carbon atom in either of the dicarbollide ion cagesof the metal dicarbollide complex. In one presently particularlypreferred embodiment, the dicarbolIide ion complexes of the inventioncomprise at least one R-group substituent having a fluorinated moietycapable of enhancing solubility in fluorinated hydrocarbon solvents, orhaving an alkyl moiety with a hydrophobicity value (π) greater thanabout 4.0, as determined using the procedure of Hansch et al. ExploringQSAR--Fundamentals and Applications in Chemistry and Biology, AmericanChemical Society 1995, the disclosure of which is incorporated herein byreference. The hydrophobicity value represents the contribution of thesubstituent to a partition coefficient (P) of a compound containing thesubstituent in a 1-octanol/water partition system. The hydrophobicityvalues of some illustrative substituents for use in connection with thepresent invention are as follows:

    ______________________________________                                        Substituent         π                                                      ______________________________________                                        n-heptyl            4.44                                                      n-octyl             4.96                                                      n-dodecyl           5.88                                                      tetradecyl          6.98                                                      heptamethyltrisiloxy                                                                              4.20                                                      nonamethyltetrasiloxy                                                                             4.80                                                      undecamethylpentasiloxy                                                                           5.40                                                      tridecamethylhexasiloxy                                                                           6.00                                                      pentadecamethylheptasiloxy                                                                        6.60                                                      heptadecamethyloctasiloxy                                                                         7.10                                                      nonamethylnonasiloxy                                                                              7.70                                                      ______________________________________                                    

Representative extraction agents of the invention are substituteddicarbollides comprising a compound selected from the group consistingof:

a) a metal dicarbollide ion of the formula:

    M(B).sub.9 C.sub.2 H.sub.10-a R.sub.a+1).sub.2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si--O--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[Si(R"')(R')--O--].sub.e- -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3 ;

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2 ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted aikyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, --Si(R')₂ (C₆ H₅) or R"', k is 1 to 10, and R',R", R"', b, c and d are as defined above; and R₂ is selected from thegroup consisting of chlorine, bromine, methyl and trifluoromethyl;provided that at least one R must be R₁. The extraction agents of theinvention additionally comprise the conjugate acid of each of thesubstituted metal dicarbollides of the invention. As used herein, theterm "alkyl" is intended to include straight chain alkyl groups, as wellas the branched chain isomers thereof (i.e., the iso-, sec-, tert-, andother branched chain isomeric forms).

Representative extraction agents of the invention includebis(substituted-dicarbollyl) transition metal(III) anions that compriseat least one R₁ substituent. Optionally, the extraction agents of theinvention may be "mixed" substituted metal dicarbollide ions; i.e.,where one of the dicarbollyl groups contains an R₁ substituent, whereasthe other contains an R₂ substituent. Representative extraction agentsof the invention also include metal dicarbollide ion-substitutedsilicones (organosiloxanes). For convenience, the extraction agents ofthe invention are simply referred to as "substituted metal dicarbollideions." The extraction agents of the present invention differstructurally from unsubstituted metal dicarbollide ions in that at leastone hydrogen atom in either or both dicarbollyl groups has been replacedwith a non-hydrogen functional group (e.g., R₁, R₂, etc.) capable ofincreasing the solubility of the complex in water immiscible solvents.Thus, representative, but nonlimiting examples of extraction agents ofthe invention include bis(1-n-heptyl-dicarbollide),bis(1-n-octyl-dicarbollide), bis(1-n-nonyl-dicarbollide),bis(1-n-decyl-dicarbollide), bis(1-iso-heptyl-dicarbollide),bis(1-iso-octyl-dicarbollide), bis(1-iso-nonyl-dicarbollide),bis(1-iso-decyl-dicarbollide), bis(1-sec-heptyl-dicarbollide),bis(1-sec-octyldicarbollide), bis(1-sec-nonyl-dicarbollide),bis(1-sec-decyl-dicarbollide), bis(1-tert-heptyl-dicarbollide),bis(1-tert-octyl-dicarbollide), bis(1-tert-nonyl-dicarbollide), andbis(1-tert-decyl-dicarbollide), bis(1-perfluoroethyl-dicarbollide),bis(1-perfluoropropyl-dicarbollide), bis(1-perfluorobutyl-dicarbollide),bis(1-perfluoropentyl-dicarbollide), bis(1-perfluorohexyl-dicarbollide),bis(1-perfluoroheptyl-dicarbollide), bis(1-perfluorooctyl-dicarbollide),bis(1-perfluorononyl-dicarbollide), bis(1-perfluorodecyl-dicarbollide),bis[6-(o-fluorophenyl)dicarbollide, bis[6-(m-fluorophenyl) dicarbollide,and bis[6-(p-fluorophenyl) dicarbollide, tetramethylphenyldisiloxydicarbollide, pentamethyldisiloxy dicarbollide,hexamethylphenyltrisiloxy dicarbollide, heptamethyltrisiloxydicarbollide, octamethylphenyltetrasiloxy dicarbollide,nonamethyltetradisiloxy dicarbollide, decamethylphenylpentasiloxydicarbollide, undecamethylpentasiloxy dicarbollide,tridecamethylhexasiloxy dicarbollide, pentadecamethylheptasiloxydicarbollide, heptadecamethyloctasiloxy dicarbollide,nonamethylnonasiloxy dicarbollide, bis[1-(n-ethyl)-dicarbollyl]metalanion substituted silicone, bis[1-(n-propyl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-butyl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-pentyl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-hexyl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-heptl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-octyl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-nonyl)-dicarbollyl]metal anionsubstituted silicone, bis[1-(n-decyl)-dicarbollyl]metal anionsubstituted silicone, and the straight and/or branched chain isomersthereof.

Thus, for the 1,2-dicarbollide isomer, each of the dicarbollyl groupshas at least one R₁ group bound to a boron atom (at either the 6 or 8positions) or a carbon atom. Similarly, for the 1,7-dicarbollide isomer,each of the dicarbollide groups has at least one R₁ group bound to aboron atom (at either the 2 or 9 positions) or to a carbon atom. Formixed R-substituent dicarbollides, an R₁ group is bound to a boron orcarbon atom in one of the dicarbollide ion cages, and an R₂ group isbound to a boron or carbon atom in the other dicarbollide ion cage. Fordicarbollide substituted silicones, a boron atom in one of thedicarbollide ion cages of the metal dicarbollide ion moiety is bound toan oxygen atom or alkylene group, (--CH₂ --)₂₋₁₀, which is bound to asilicon atom in the backbone of an organosiloxane. Alternatively, acarbon atom in one of the dicarbollide ion cages is bound to an alkylenegroup, which is bound to a silicone atom in the backbone of theorganosiloxane. In either case, the other dicarbollyl group may alsobear a non-hydrogen substituent.

Additionally, in some embodiments, the extraction agents are brominatedor chlorinated. Each 1,2-dicarbollyl group can contain up to three Br orCl atoms in place of H atoms. Generally, such substitution by halogenoccurs at the 8, 9, 12, 8', 9', and/or 12' positions. (The prime (')symbol distinguishes between the two dicarbollyl groups of the complex.)Each 1,7-dicarbollide group can contain up to two Br or Cl atoms inplace of H atoms or hydrocarbon substituents. Generally, suchsubstitution by halogen occurs at the 9, 10, 9' and/or 10' positions.

Alkyl- and phenyl-substituted metal dicarbollide ions exhibit increasedsolubility in hydrocarbon solvents such as kerosene and xylene, and in1-octanol, tributylphosphate, and similar solvents. Fluorinated alkyl-and phenyl-substituted metal dicarbollide ions tend to be soluble influorinated alkanes and arenes such as fluorinated kerosene, fluorinatedbiphenyl compounds, fluorinated polyether compounds such as Fomblin Yvacuum pump oil (a perfluoro polyether available from Montedison USA,Inc., Aldrich), and other fluorinated hydrocarbon solvents.Organosiloxane-substituted metal dicarbollide ions are soluble insilicone oils and elastomers.

The extraction agents of the invention are prepared in a straightforwardmanner from carborane (B₁₀ C₂ H₁₂), transition metal halides (e.g.,CoCl₂.nH₂ O, FeCl₂, etc.), unsubstituted metal dicarbollide ions, M(B₉C₂ H₁₁)₂ ⁻, and/or other reactants. The particular starting matedais andreaction methodologies used depend on several factors, including theempirical formula of the extraction agent being prepared, the particularisomer being prepared (i.e., is the solubilizing chemical moiety bondedto a boron atom or a carbon atom, and at which position) and, in somecases, the identity of the metal atom in the complex. For example,substituted chromium dicarbollide ions are conveniently prepared underanhydrous conditions, but are more difficult to make under aqueousconditions. Cobalt ions, on the other hand, are conveniently preparedunder both aqueous and anhydrous conditions.

General synthetic routes to the extraction agents of the presentinvention will now be described.

1. Substituted Metal Dicarbollide Ions of the Formula: M(B₉ C₂ H_(10-a)R_(a+1))₂ ⁻ ; R is Bound to Carbon

a. Non-halogenated 1,2-Dicarbollide Complexes

The general synthetic scheme entails reacting decaborane (B₁₀ H₁₄) witha terminal alkyne (RCCH) in the presence of an electron donor molecule,such as acetonitrile or dialkyl sulfide (:L) to form an R-substituted1,2-carborane, (1-R-1,2-B₁₀ C₂ H₁₁ CF₃)⁻. Degradation of 1,2-carboranewith methanolic base (NaOH in CH₃ OH) yields 1-R-substituteddicarbadodecahydroundecaborate (-1) ion (1,2-B₉ C₂ H₁₁ R⁻). (Forexample, 1-propyne yields (B₉ C₂ H₁₁ CH₃)⁻ ; 3,3,3-trifluoro-1-propyneyields (B₉ C₂ H₁₁ CF₃)⁻ ; etc.

Reaction with a transition metal halide yields an R-substituted metaldicarbollide ion, M(B₉ C₂ H₁₀ R)₂ ⁻ (more precisely, a bis(R-substituted-1,2-di-carbollyl)metal(III)(-1) ion, as a mixture of 1-R- and2-R-substituted isomers.

Thus, the first two steps of the synthesis are: ##STR1## The metaldicarbollide ion can be formed by reacting the R-substituteddicarbadodecahydroundecaborate (-1) ion with a metal halide, in thepresence of an aqueous base. Thus, for cobalt, the reaction is ##STR2##

Alternatively, the substituted metal dicarbollide ion is formed using anon-aqueous approach. First, theR-substituted-dicarbadodecahydroundecaborate anion is isolated as thetrimethylammonium salt (by, e.g., treating it with an aqueous solutionof trimethylammonium chloride). The salt is then reacted with sodiumhydride (NaH) in dry tetrahydrofuran (THF), yielding an anhydrous THFsolution of an R-substituted dicarbollide ion (B₉ C₂ H₁₀ R)²⁻.(Trimethylamine is evolved as a gas.) Reaction with an anhydrous metalhalide yields the R-substituted transition metal dicarbollide ion:##STR3##

Whether prepared under aqueous or nonaqueous conditions, the substitutedmetal dicarbollide ion can be isolated as a salt (for example, a cesiumsalt, by treatment with CsCl) and, if desired, can be converted to theconjugate acid, [H⁺ ][M(B₉ C₂ H₁₀ R)₂ ⁻ ], either by reaction with astrong mineral acid or by passage through a protonated ion exchangecolumn.

b. Halogenated Complexes

Transition metal dicarbollide complexes and their derivatives can bechlorinated or brominated by elemental halogen in polar solvents.Substitution proceeds in the unsubstituted complex alternativelyin bothcages yielding successively 8-; 8,8'-; 8,9,8'-; 8,9,8',9'-;8,9,12,8',9'- and 8,9,12,8',9',12'-halogen derivatives. The degree ofhalogenation is controlled by the reagent stoichiometry and reactionconditions.

c. Non-Halogenated, 1,7-Dicarbollide Complexes

Meta-Carborane (1,7-B₁₀ C₂ H₁₂) is prepared by thermal rearrangement ofthe carbon atoms in ortho-carborane (1,2-B₁₀ C₂ H₁₂) using well knownliterature methods. See, e.g., Beall, "Icosahedral Carboranes," BoronHydride Chemistry, Chapter, 9, Muetterties, Ed., Academic Press, Inc.,1975. Degradation of meta-carborane to1,7-dicarbadodecahydroundecaborate(-1) and subsequent proton removal toproduce 1,7-dicarbollide ion is accomplished by literature methodssimilar to those described for the 1,2- isomer above. See, e.g.,Hawthorne et at., "The Preparation and Characterization of the 1,2- and1,7-Dicarbadodecahydroundecaborate (-1) Ions," J. Amer. Chem. Soc.90:862 (1968), and Hawthome et at., "Pi-Dicarbollyl Derivatives of theTransition Metals. Metallocene Analogs," J. Amer. Chem. Soc. 90:879(1968), and Ruhle et at., Inorg. Chem. 7:2279 (1968).

d. Halogenated, Metal 1,7-Dicarboilide Complexes

Transition metal 1,7-dicarbollide complexes and their derivatives can bechlorinated or brominated by elemental halogen in polar solvents.Substitution proceeds in the unsubstituted complex alternatively in bothcages yielding successively 9-; 9,9'-; 9,9',10-; and 9,9',10,10'-halogen derivatives. The degree of halogenation is controlled by thereagent stoichiometry and reaction conditions.

2. Substituted Metal Dicarbollide Ions of the Formula: M(B₉ C₂ H_(10-a)R_(a+1))₂ ⁻ ; R is Bound to Boron

a. Non-halogenated 1,2-Complexes Substituted at the 6 Position

The general synthetic scheme entails reacting unsubstituted1,2-dicarbollide ion (1,2-B₉ C₂ H₁₁ ⁻²) with an R-substituted borondichloride (RBCl₂) to form a 3-R-substituted ortho-carborane (moreprecisely, a 3-R-1,2-dicarba-closo-dodecaborane, B₁₀ C₂ H₁₁ R).

Reaction of the 3-R-substituted ortho-carborane with methanolic baseyields an R-substituted 1,2-dicarbadodecahydroundecaborate (-1)ion (B₉C₂ H₁₁ R⁻), which is substituted at the 6 position. Typically, the ionis isolated as a trimethylammonium salt, by, e.g., precipitation withtrimethylammonium chloride.

The R-substituted 1,2-dicarbadodecahydroundecaborate (-1) ion is treatedwith sodium hydride in dry THF, forming an R-substituted dicarbollideion (B₉ C₂ H₁₀ R⁻²), which is then reacted with an anhydrous metalhalide in dry THF to form an R-substituted metal dicarbollide ion inwhich each dicarbollyl group carries an R group (instead of H) at the 6position.

b. Non-Halogenated, 1,7-Dicarbollide Complexes Substituted at the 2Position

The general synthetic scheme entails reacting unsubstituted1,7-dicarbollide ion (1,7-B₉ C₂ H₁₁ ⁻²) with an R substituted borondichloride (RBCl₂) to form 2-R-1,7-dicarba-closo-dodecaborane, 1,7-B₁₀C₂ H₁₁ R. Reaction of the 2-R-substituted meta-carborane with methanolicbase yields R-substituted 1,7-dicarbadodecahydro-undecaborate(-1) ion(1,7-B₉ C₂ H₁₁ R⁻), which is substituted at the 2 position. Typically,the ion is isolated as the trimethylammonium salt by e.g., precipitationwith trimethylammonium chloride. The trimethylammonium. salt of2-R-1,7-dicarbado-decahydroundecaborate(-1) ion is treated with sodiumhydride in dry THF, forming R-substituted 1,7-dicarbollide ion (1,7-B₉C₂ H₁₀ R⁻²), which is then reacted with an anhydrous metal halide in dryTI-IF of form an R-substituted metal 1,7-dicarbollide complex in whicheach dicarbollyl group carries an R group (instead of H) at the 2position. The entire schematic synthesis, beginning with 1,2-carboraneor 1,7-carborane, is shown below, for cobalt: ##STR4##

The substituted metal dicarbollide ion can be isolated as a salt or asthe conjugate acid using the procedure(s) discussed above.

The synthesis of unsubstituted dicarbollide ion is well known, andentails degrading ortho-carborane with methanolic base, followed byreaction of the resulting 1,2-dicarbadodecahydroundecaborate (-1) ion(B₉ C₂ H₁₂ ⁻) with sodium hydride in anhydrous THF.

R-substituted boron dichlorides (RBCl₂) can be prepared by reaction ofboron trichloride with active R-substituted metals, such as Grignardreagents, R-substituted zinc or R-substituted tin compounds. As anillustrative example, C₆ H₅ BCl₂ may be obtained according to thefollowing reaction:

    BCl.sub.3 +C.sub.6 H.sub.5 MgCl→C.sub.6 H.sub.5 BCl.sub.2 +MgCl.sub.2

c. Non-halogenated 1,2-Complexes Substituted at the 8 Position

In general, bis(8-R-1,2-dicarbollyl) metal (III) ions (also called8-R-substituted metal 1,2-dicarbollide ions) are easier to prepare thanthe 3-substituted isomers. The general reactive scheme entails reactingiodine (I₂) with an unsubstituted metal 1,2-dicarbollide ion [M(B₉ C₂H₁₁)₂ ⁻ ] to form an 8-iodo-metal 1,2-dicarbollide ion [M(8-I-1,2-B₉ C₂H₁₀)₂ ⁻ ], followed by reaction with a Grignard reagent, RMgX (X is Br,Cl or I) in the presence of a catalyst to form an 8-substituted metal1,2-dicarbollide ion.

d. Non-Halogenated 1,7-Dicarbollide Complexes Substituted at the 9Position

In general, bis(9-R-1,7-dicarbollyl) metal complexes are easier toprepare than the 2-substituted isomers. The general reactive schemeentails reacting iodine (I₂) with unsubstituted 1,7-dicarbollide metalcomplex M(1,7-B₉ C₂ H₁₁)₂ ⁻ to form 9-iodo-metal dicarbollide ionM(9-I-1,7-B₉ C₂ H₁₀)₂ ⁻, followed by reaction with a Grignard reagent,RMgX (X is Br, Cl or I) in the presence of a catalyst to form9-substituted metal 1,7-dicarbollide ion.

Illustrative reactions for both the 1,2- and 1,7-dicarbollide complexesmay be represented as follows: ##STR5##

Alkyl and branched alkyl derivatives of bis-[(1,2-B₉ C₂ H₁₁)₂ ]M⁻ in the8,9,12,8',9',12' positions and bis-[(1,7-B₉ C₂ H₁₁)₂ ]M⁻ in the9,10,9',10' positions can be prepared by Fdedel-Crafts alkylation using,for example, alkyl halides with Lewis acid catalysts such as aluminumchloride. As a representative example, bis[9,10-(sec--C₄ H₉)₂-1,7-dicarbollyl]cobalt(III) may be prepared according to the followingreaction.

Illustrative reactions for both the 1,2- and 1,7-dicarbollide complexesmay be represented as follows: ##STR6## as is more fully described inExample 6.

The syntheses of several unsubstituted metal dicarbollide ions has beenreported and is well known. See, e.g., Hawthome et al., "Pi-DicarbollylDerivatives of the Transition Metals. Metallocene Analogs," J. Amer.Chem. Soc. 90:879 (1968), and Ruhle et al., Inorg. Chem. 7:2279 (1968),both of which are incorporated herein by this reference.

e. Halogenated 1,2-Dicarbollide Complexes Substituted at the 6 or 8Position

Transition metal 1,2-dicarbollide complexes can be R-substituted in the6 or 8 position as described above. Both types of substituted complexcan be chlorinated or brominated by elemental halogen in polar solvents.In the 6-substituted complex, halogen substitution proceeds in bothcages yielding successively 8-; 8,8'-; 8,9,8'-; 8,9,8',9'-;8,9,12,8',9'- and 8,9,12,8',9',12'-halogen derivatives. In the8-substituted complex, halogen substitution proceeds in both cagesyielding successively 9,9'-; 9,12,9'- and 9,12,9',12'-halogenderivatives. In both cases, the degree of halogenation is controlled bythe reagent stoichiometry and reaction conditions. f. Halogenated1,7-Dicarbollide Complexes Substituted at the 2 or 9 Positions

Transition metal 1,7-dicarbollide complexes and their derivatives can bechlorinated or brominated by elemental halogen in polar solvents.Halogenation proceeds in the complex substituted in the 2 positionalternatively in both cages yielding successively 9-; 9,9'-; 9,9',10-;and 9,9',10,10'- halogen derivatives. Halogenation proceeds in thecomplex substituted in the 9 position alternatively in both cagesyielding successively 10-; and 10,10'- halogen derivatives. The degreeof halogenation is controlled by the reagent stoichiometry and reactionconditions.

3. Preparation of "Mixed" Substituted Metal Dicarbollide Ions of theFormula: (B₉ C₂ H_(10-a) (R₁)M(B₉ C₂ H_(10-a) (R₂)_(a+1))

The reaction scheme entails treating equimolar mounts of thetrimethylammonium salts of R₁ -substituteddicarbadodecahydroundecaborate (-1) and R₂ -substituteddicarbadodecahydroundecaborate (-1) ions with excess sodium hydride toform a mixture of R₁ - and R₂ - substituted dicarbollide ions, andtreatment of the mixture with an anhydrous metal halide in THF to formcomplex ions. When R₂ is methyl (--CH₃), and the reactants and productsare non-halogenated, the general reaction is: ##STR7##

A similar scheme can be written out for R₂ =trifluoromethyl (--CF₃).

The monoanions, [B₉ C₂ H₁₁ (R₁)]⁻ and [B₉ C₂ H₁₁ (R₂)]⁻, where R₁ and R₂are as defined above, and their trimethylammonium salts, are prepared inaccordance with the procedures described above.

Transition metal 1,2- and 1,7-dicarbollide complexes and their "mixed"derivatives can be chlorinated or brominated by elemental halogen inpolar solvents. Halogenation proceeds at the unsubstituted, labile boronatoms in the sequences discussed above for the 1,2- and 1,7-dicarbollidecomplexes respectively. The degree of halogenation is controlled by thereagent stoichiometry and reaction conditions.

4. Preparation of Metal Dicarbollide Ion--Substituted Organosiloxanes

Siloxane substituted transition metal dicarbollide complexes areproduced by classical silicon chemistry methods. For example,chlorosilanes (.tbd.Si--Cl) react with hydroxyl groups (R-OH) to form.tbd.Si--O--R, hydrosilanes (.tbd.Si-H) add to unsaturated hydrocarbons(R--CH═CH₂) to form .tbd.Si--CH₂ CH₂ -R and nucleophilic reagents (R⁻)attack silicon-chlorine bonds (.tbd.Si'Cl) to form .tbd.Si-R. ThusCs{[8-(OH)-1,2-B₉ C₂ H₁₀ ]₂ Co} reacts with Cl--Si(CH₃)₂ O--Si(CH₃)₂ C₆H₅ to produce Cs{[8--Si(CH₃)₂ --C₆ H₅ --O--Si(CH₃)₂ --O--1,2-B₉ C₂ H₁₀]₂ Co} and Cs{[1--CH₂ ═CHCH₂ CH₂ -1,2-B₉ C₂ H₁₀ ]Co[1--CH₃ -1,2-B₉ C₂H₁₀ ]} reacts with H--Si(CH₃)₂ --O--[Si(CH₃)₂ --O--]_(n) --Si(CH₃)₃ toproduce Cs{[1--Si(CH₃)₃ --O--[Si(CH₃)₂ --O--]_(n) --Si(CH₃)₂ --CH₂ CH₂CH₂ CH₂ -1,2-B₉ C₂ H₁₀ ]Co[1--CH₃ -1,2-B₉ C₂ H₁₀ ]}. Finally, atransition metal dicarbollide complex can act as an acid and donate aproton from a cage carbon atom to strong bases such as lithiumdiisopropylamide (Aldrich, Inc.), butyl lithium or sodium hydride toproduce a nucleophilic anion (e.g., Cs[B₉ C₂ H₁₁)Co(LiB₉ C₂ H₁₀)]). Thenucleophilic anion can then attack the silicon-chlorine bond such asthat in Cl--Si(CH₃)₂ --O--Si(CH₃)₂ C₆ H₅ to produce Cs{(B₉ C₂ H₁₁)CoB₉C₂ H₁₀ -[Si(CH₃)₂ --O--Si(CH₃)₂ C₆ H₅ ]}.

Extraction of Cesium and Strontium

In addition to the novel extraction agents described above, the presentinvention also provides new methods or processes for extracting cesiumand strontium ions from aqueous solutions, such as aqueous fissionproduct waste solutions. In one such process, cesium and/or strontiumions are extracted from an aqueous solution by passage through a unique,semipermeable membrane comprising either a modified silicone polymercontaining pendant metal dicarbollide ion moieties, or a microporouspolymer film impregnated with substituted maal dicarbollide ions. Inanother process, cesium and strontium are extracted by solventextraction, using a nonaqueous phase in which are dissolved substitutedmetal dicarbollide ions of the type described above.

In both types of extraction processes, it is convenient to distinguishbetween "pregnant" and "stripped" phases. A "pregnant" phase or solutioncontains a substance, such as an ion, which is to be extracted. Thus, anaqueous solution containing cesium and/or strontium ions is referred toas a "pregnant phase" or "pregnant solution." After the ions areextracted into a nonaqueous phase, the aqueous solution is referred toas the "stripped phase"--ions have been stripped from it--and thenonaqueous phase (which now contains Cs⁺ and/or Sr⁺² ions) is referredto as a "pregnant nonaqueous phase."

In one embodiment of the invention, schematically illustrated in FIG. 1,extraction proceeds without the use of a nonaqueous phase. An aqueoussolution containing cesium (Cs⁺) and strontium (Sr⁺²) ions, such as anaqueous solution of fission product waste, is placed in the leftcompartment 11 of a cell 10. The right compartment 12 of the cell ischarged with an aqueous solution of mineral acid, such as hydrochloricacid, nitric acid or sulfuric acid. The aqueous mineral acid solutionpreferably has a concentration of about 0.001M to about 3.0M, morepreferably about 0.01M to about 2.0M, and most preferably about 0.05M toabout 1.0M. The two compartments of the cell 10 are separated by asemipermeable membrane 13, which allows the passage of Cs⁺, Sr⁺², and H⁺through the semipermeable membrane 13 between the two compartments 11and 12.

In one embodiment, the semipermeable membrane comprises a thin, modifiedsilicone elastomer containing metal dicarbollide ions chemically boundthereto. More particularly, the modified silicone elastomer is a metaldicarbollide ion-substituted organosiloxane as described above, with amolecular weight and organic groups (R', R") such that it is anelastomer, rather than an oil. In another embodiment, the membranecomprises a thin, microporous polymer film in which are immobilizedprotonated substituted metal dicarbollide ions of the type describedabove. Examples of such microporous films include Celgard 2500, sold byCelanese Plastics Co., and Accurel, sold by Enka Membrane. Both productsare composed of polypropylene. Example 9, below, describes theimpregnation of such a film with a protonated substituted metaldicarbollide ion prepared in accordance with the present invention.

According to this process, first Cs⁺ ions and then Sr⁺² ions areextracted into the right compartment 12 containing mineral acid.Agitation, such as by a mechanical stirrer (not shown) causes theconcentration of Cs⁺ and Sr⁺² ions to be essentially constant throughoutthe left compartment 11 containing aqueous waste, and maximizes thenumber of Cs⁺ and Sr⁺² ions impinging on (and diffusing through) themembrane per unit time.

Diffusion of cesium ions into and through the membrane is facilitated byassociation with the protonated metal dicarbollide ion complexes withinthe membrane, which simultaneously release hydrogen ions into theaqueous fission product solution. As the cesium ions pass from themembrane into the hydrochloric acid solution, they are replaced in themembrane by hydrogen ions from the hydrochloric acid solution. Thus, thenet process is the passage of cesium ions from the fission productsolution through the semipermeable membrane to the hydrochloric acidsolution, and the passage of hydrogen ions from the hydrochloric acidsolution through the membrane to the fission product solution.

Once equilibrium is achieved, the hydrochloric acid solution may beremoved and evaporated to yield cesium chloride. The hydrochloric acidvapor that is produced can then be condensed and recycled. Recycledand/or fresh hydrochloric acid solution is then added to the rightcompartment of the cell and the process resumed. The process is repeatedas many times as required to achieve the desired degree of extraction.

After most of the cesium ion has been extracted from the fission productsolutions, strontium ion can be removed. A quantity of polyethyleneglycol (such as PEG-400) or p-nonylphenylnonaethylene glycol (such asSlovafol-909) is added to the aqueous fission product solution tofacilitate the diffusion of strontium ions into the semipermeablemembrane. Once in the membrane, the strontium ions diffuse through themembrane, facilitated by the metal dicarbollide ions contained therein,and into the hydrochloric acid solution in the right compartment of thecell. The strontium ions are replaced in the membrane by hydrogen ionsfrom the hydrochloric acid solution. The net effect is the passage ofstrontium ions from the fission product solution through thesemipermeable membrane to the hydrochloric acid solution, and thepassage of hydrogen ions from the hydrochloric acid solution through themembrane to the fission product solution. Once equilibrium is achieved,the hydrochloric acid solution is removed and evaporated to isolatesolid strontium chloride.

Example 14, below describes another representative embodiment of theinvention in which cesium ions are extracted from an aqueous solutionusing the conjugate acid of a metal dicarbollide ion-substitutedsilicone oil immobilized in an Accurel polypropylene film. The H cell isschematically illustrated in FIG. 2.

In yet another embodiment of the invention, extraction proceeds by asimple mixing and separation process similar to that encountered when aseparatory funnel is used to extract a substance from an aqueoussolution into a nonaqueous solution. In this embodiment, cesium ions areextracted from a pregnant aqueous phase into a nonaqueous phasecontaining at least one substituted metal dicarbollide ion extractionagent of the invention. For this purpose, the nonaqueous phasepreferably contains a concentration of the extraction agent of fromabout 0.005M to about 0.50M, more preferably from about 0.007M to about0.20M, and most preferably from about 0.010 to about 0.10M in a suitablesolvent for the extraction agent. The choice of desireable solvents foruse in the practice of the invention will depend on the particularextraction agent employed. For example, when the extraction agent is aalkyl- or phenyl-substituted metal dicarbollide ion, as described indetail above, representative solvents include hydrocarbon solvents suchas, for example, kerosene and xylene, and 1-octanol, tributylphosphate,and similar hydrocarbon and phosphate solvents. When the extractionagent is a fluorinated alkyl- or phenyl-substituted metal dicarbollideion of the invention, representative solvents include fluorinatedalkanes and arenes such as fluorinated kerosene, fluorinated biphenylcompounds, fluorinated polyether compounds such as Fomblin Y vacuum pumpoil (a perfluoro polyether available from Montedison USA, Inc.,Aldrich), and other fluorinated hydrocarbon solvents. As used herein,the term "fluorinated hydrocarbon solvents" is intended to include anyhydrocarbon solvent containing one or more fluorine substituents, e.g.,mono-fluoro, difluoro, etc. up to perfluorinated hydrocarbons. When theextraction agent is an organosiloxane-substituted metal dicarbollide ionof the invention, representative solvents include silicone oils, such asthe silicone oils PS 042 and PS 043 available from United ChemicalTechnologies, Inc., Bristol, Pa., USA, and other similar silicone oils.

The result is isolation of cesium ions from the other components (e.g.,radionuclides) present in the original aqueous phase. Thereafter, theextracted cesium ions are readily stripped from the nonaqueous phase(which is considered "pregnant" with cesium ions) by treatment with amineral acid, such as hydrochloric, nitric, or sulfuric acid, asdescribed above. Strontium ions are then extracted from the originalaqueous phase by first adding polyethylene glycol orp-nonylphenylnonaethylene glycol (which form a complex with Sr⁺² ions,rendering them more hydrophobic), and extracting the Sr⁺² from theaqueous phase to a nonaqueous phase. As with Cs⁺, the Sr⁺² ions can thenbe stripped from the nonaqueous phase by treatment with a mineral acid.

Thus, cesium ions are conveniently extracted from an aqueous solution,or phase, by first forming an aqueous-nonaqueous liquid combination bycontacting a pregnant aqueous phase containing cesium ions with a firstnonaqueous phase containing a substituted metal dicarbollide extractionagent of the invention. The liquid combination is then separated into anaqueous phase which has a diminished cesium ion concentration and apregnant nonaqueous phase which contains cesium ions extracted from theoriginal, pregnant aqueous phase. Essentially, the interface betweenaqueous and nonaqueous phases in the liquid combination functions as aliquid membrane through which cesium ions pass. Although not bound bytheory, it is believed that the substituted metal dicarbollide ionsfacilitate passage of cesium ions through the interface by formingneutral ion pairs with the cesium cations. After the cesium ions havebeen extracted into the nonaqueous phase, they can be stripped therefromby treatment with mineral acid. Once extracted, the stripped cesium ionscan be isolated as a cesium salt.

Strontium ions can be extracted from an aqueous solution in a similarmanner. Preferably, the pregnant aqueous solution is substantiallycesium-free, that is, most of the cesium originally present in thesolution has already been removed by a prior extraction. Strontium isextracted by first adding polyethylene glycol orp-nonaphenylnonaethylene glycol to the pregnant aqueous phase. Anaqueous-nonaqueous liquid combination is then formed by contacting thepregnant aqueous phase with a first nonaqueous phase containing asubstituted metal dicarbollide ion. The liquid combination is thenseparated into a stripped aqueous phase (which is diminished instrontium ion concentration) and a pregnant nonaqueous phase (whichcontains strontium ions extracted from the original pregnant aqueousphase). As was the case with cesium, strontium ions can then be strippedfrom the pregnant nonaqueous phase by treatment with mineral acid.

In practice, aqueous fission product waste solutions contain both cesiumand strontium ions. Thus, the present invention provides extractionprocesses for selectively extracting both cesium and strontium ions,sequentially. More particularly, cesium and strontium ions areselectively extracted from an aqueous solution by (a) forming a firstaqueous-nonaqueous liquid combination by contacting a pregnant aqueousphase containing cesium and strontium ions with a first nonaqueous phasecontaining substituted metal dicarbollide ions; (b) separating the firstliquid combination into a stripped aqueous phase and a pregnantnonaqueous phase, wherein the pregnant nonaqueous phase contains cesiumions extracted from the pregnant aqueous phase; (c) modifying thestripped aqueous phase by adding a polyethylene glycol orp-nonaphenylnonaethylene glycol; (d) forming a second aqueous-nonaqueousliquid combination by contacting the modified, stripped aqueous phasewith a fresh nonaqueous phase containing substituted metal dicarbollideions; and (e) separating the second liquid combination into a secondstripped aqueous phase and a second pregnant nonaqueous phase, whereinthe second pregnant nonaqueous phase contains strontium ions extractedfrom the preceding aqueous phase.

Extraction efficiency can be increased by repeating each of theindividual extraction steps, as may be desired. Thus, cesium ions areconveniently and efficiently extracted from an aqueous solution byalternately exposing a nonaqueous liquid containing substituted metaldicarbollide ions to (a) a pregnant aqueous solution containing cesiumions; and (b) an aqueous solution of mineral acid.

Similarly, strontium ions are more efficiently extracted from an aqueoussolution by alternately exposing a nonaqueous liquid containingsubstituted metal dicarbollide ions to (a) a pregnant aqueous solutioncontaining strontium ions and polyethylene glycol orp-nonaphenylnonaethylene glycol, and (b) an aqueous solution of mineralacid.

FIGS. 3 and 4 schematically illustrate a continuous process forselectively and efficiently extracting first cesium and then strontiumfrom an aqueous solution (such as aqueous fission product waste). Thus,in FIG. 3 a nonaqueous liquid less dense than the aqueous waste solutionand containing substituted metal dicarbollide ions is altemately exposedto an aqueous fission product solution in one compartment and an aqueoussolution of mineral acid in another compartment.

A mechanical stirrer (not shown), or other agitation means, agitates theaqueous phase and increases the interaction between aqueous andnonaqueous phases. Cesium ions, facilitated by the substituted metaldicarbollide ions, diffuse into the nonaqueous phase. Simultaneously,hydrogen ions diffuse from the nonaqueous liquid into the fissionproduct solution, thus maintaining electrical charge neutrality.

The nonaqueous liquid, laden with cesium ions, is mechanicallytransferred to another compartment containing hydrochloric acid.(Alternatively, another mineral acid can be used.) In FIG. 3, a pump isused to transfer the nonaqueous liquid between compartments.Alternatively, other means (not shown) may be used. Cesium ions diffusefrom the nonaqueous liquid into the hydrochloric acid, with simultaneousdiffusion of hydrogen ions from the hydrochloric acid to the nonaqueousliquid.

As the nonaqueous liquid is pumped from compartment (A) to compartment(B), the level of the nonaqueous liquid rises until it overflows fromcompartment (B) to compartment (A). Thus, the system is continuous, withthe net effect being transfer of cesium ions from compartment (A) tocompartment (B) and transfer of hydrogen ions from compartment (B) tocompartment (A). Periodically, hydrochloric acid solution is drained toan evaporator where the water and hydrogen chloride are removed, leavingsolid cesium chloride.

After removal of most, or substantially most of the cesium, polyethyleneglycol or p-nonaphenylnonaethylene glycol is added to the aqueousfission product solution in compartment (A) to facilitate the diffusionof strontium ion as a hydrophobic complex from the aqueous phase intothe nonaqueous liquid. Diffusion of the strontium ion complex within thenonaqueous liquid is facilitated by the substituted metal dicarbollideions contained therein. The nonaqueous liquid, laden with strontiumions, is mechanically transferred to compartment (B) containing stirredhydrochloric acid. Strontium ions diffuse from the nonaqueous liquidinto the hydrochloric acid with simultaneous diffusion of hydrogen ionsfrom the hydrochloric acid into the nonaqueous liquid.

As the nonaqueous liquid is pumped from compartment (A) to compartment(B), the level of the nonaqueous liquid rises until it overflows fromcompartment (B) to compartment (A). Thus, the system is continuous, withthe net effect being transfer of strontium ions from compartment (A) tocompartment (B) and transfer of hydrogen ions from compartment (B) tocompartment (A). Periodically, hydrochloric acid solution is drained toan evaporator where the water and hydrogen chloride are removed, leavingsolid strontium chloride.

FIG. 4 schematically illustrates an alternate embodiment of theinvention in which a nonaqueous liquid more dense than the aqueousfission product solution and containing substituted metal dicarbollideions is alternately exposed to aqueous fission product solution incompartment (A) then hydrochloric acid solution in compartment (B). (InFIG. 4, perfluorokerosene is shown as the denser, nonaqueous phase.Persons skilled in the art will appreciate that other solvents, having adensity greater than the aqueous phase, can also be used.)

A mechanical stirrer (not shown), or other agitation means, agitates thenonaqueous phase and increases the interaction between aqueous andnonaqueous phases. Cesium ions diffuse into the nonaqueous phase,facilitated by the substituted metal dicarbollide ions containedtherein. Simultaneously, hydrogen ions diffuse from the nonaqueousliquid into the fission product solution, thus maintaining electricalcharge neutrality.

The dense, nonaqueous liquid, laden with cesium ions can pass fromcompartment (A) to compartment (B) where it contacts stirredhydrochloric acid. Cesium ions diffuse from the nonaqueous liquid intothe hydrochloric acid with simultaneous diffusion of hydrogen ions fromthe hydrochloric acid to the nonaqueous liquid. Optionally, thenonaqueous liquid is mechanically pumped back from compartment (B) tocompartment (A). (Alternatively, other transport means (not shown) canbe used.) Thus, the system is continuous, with the net effect beingtransfer of cesium ions from compartment (A) to compartment (B), andtransfer of hydrogen ions from compartment (B) to compartment (A).Hydrochloric acid solution is periodically drained to an evaporatorwhere the water and hydrogen chloride are removed, leaving solid cesiumchloride.

After removal of most, or substantially most of the Cs⁺, polyethyleneglycol or p-nonaphenylnonaethylene glycol is added to the aqueousfission product solution in compartment (A) to facilitate the diffusionof strontium ions into the denser, nonaqueous liquid. Diffusion ofstrontium ions within the nonaqueous liquid is facilitated by thesubstituted metal dicarbollide ions contained therein.

The nonaqueous liquid, laden with strontium ions, can pass fromcompartment (A) to compartment (B) containing stirred hydrochloric acid.Strontium ions diffuse from the dense, nonaqueous liquid into thehydrochloric acid with simultaneous diffusion of hydrogen ions from thehydrochloric acid into the dense nonaqueous liquid. Optionally, thedense, nonaqueous liquid is pumped or otherwise transferred fromcompartment (B) to compartment (A). Thus, the system is continuous, withthe net effect being transfer of strontium ions from compartment (A) tocompartment (B) and transfer of hydrogen ions from compartment (B) tocompartment (A). Hydrochloric acid solution is periodically drained toan evaporator where the water and hydrogen chloride are removed leavingsolid strontium chloride.

EXAMPLES

The following examples provide non-limiting illustrations of theextraction agents and processes of the present invention, as well asmethods for making and/or using same.

1,2-Dicarbollide (-2) ion, bis[1,2-dicarbollyl]cobalt(III) (-1) (cobaltdicarbollide ion) and their 1,7-analogs may be prepared by known methods(see, e.g., J. Amer. Chem. Soc., 90:879 (1968), cited above).

Example 1 Trimethylammonium1-(n-Octyl)-1,2-dicarbadodecahydroundecaborate

A 1000 mL, 3-necked, round-bottom flask fitted with a mechanicalstirrer, reflux condenser topped with a nitrogen inlet, and a pressureequalized dropping funnel is charged with 60.0 g (0.49 mol) ofdecaborane and 450 mL of benzene. Acetonitrile (40.2 g, 0.98 mol) isadded to the flask over a 30 minute period. The solution is heated toreflux and maintained for 23 hours. The reaction mixture is cooledslightly and 89.8 g (0.54 mol) of 1-decyne is placed into the droppingfunnel. The reaction mixture is again heated to reflux and the 1-decyneis added to the flask over 5.3 hours, with reflux maintained anadditional 15 hours. The mixture is cooled to ambient temperature, andthe solvents are stripped using a rotary evaporator and a 60° C. waterbath, leaving a viscous red-brown oil (167 g). The oil is dissolved in280 mL of acetonitrile and extracted with 2600 mL of hexane for 18hours. The hexane-carborane fraction is washed with 400 mL of cold waterfollowed by four 500 mL portions of cold 10% NaOH and two 500 mLportions of water. The hexane-carborane fraction is dried over anhydrousMgSO₄ and filtered. The solvent is stripped using a rotary evaporator(mechanical pump) and a 60° C. water bath. The residual oil is heated at240° C. for 6 hours under nitrogen, then distilled (0.5 mm Hg, 129° C.)with a flask temperature of 182°-188° C., to collect 46.1 g (0.18 mol,36%) of 1-(n--C₈ H₁₇)- 1,2-B₁₀ C₂ H₁₁.

A 500 mL, three-necked flask equipped with a reflux condenser,mechanical stirrer and nitrogen inlet is charged with a solution of 20 g(0.36 mol, 100% excess) of potassium hydroxide in 300 mL of absoluteethanol. The solution is cooled to room temperature, and 46.1 g (0.18mol) of 1-(n--C₈ H₁₇)-1,2-B₁₀ C₂ H₁₁ is added. The resulting solution isstirred for 1 hour at room temperature then heated to reflux untilhydrogen evolution ceases (about 2 hours). After cooling, an additional100 mL of absolute ethanol is added. The excess potassium hydroxide isprecipitated as potassium carbonate by saturating the solution with astream of carbon dioxide. The precipitate is removed by filtration andwashed with five 50 mL portions of ethanol. The combined flltrate andwashings are evaporated to dryness to yield a crude potassium saltK[1-(n--C₈ H₁₇)-1,2-B₉ C₂ H₁₁ ]. The salt is dissolved in 150 mL ofwater, and a solution of 22.0 g (0.23 mol) of trimethylammonium chloridein water (100 mL) is added. The precipitated trimethylammonium salt isisolated by filtration, washed with 50 mL of cold water, and dried invacuo over phosphorus pentoxide to yield 51.9 g (0.17 mol, 94%) of[(CH₃)₃ NH][1-(n--C₈ H₁₇)-1,2-B₉ C₂ H₁₁ ].

Alkyl and fluoro- to perfluoroalkyl dicarbollide ions containing 1-10carbon atoms in the alkyl or fluorinated alkyl group are prepared bysimilar procedures beginning with the appropriate alkyne. See, e.g., LeBlanc et at., "The preparation of 1-hydroperfluorohexyne, octyne anddecyne," J. Fluorine Chem. 7(5):525-30 (1976), which is incorporatedherein by reference.

Example 2 Cesium Bis[1-(n-octyl)-1,2-dicarbollyl]cobalt(III)

A 4 L Edenmeyer flask containing 51.9 g (0.17 mol) of [(CH₃)₃ NH][1-(n--C₈ H₁₇)-1,2-B₉ C₂ H₁₁ ] and 1000 mL of water is cautiouslytreated with 1000 mL of hot, fleshly prepared 40% aqueous sodiumhydroxide and 66.5 g (0.28 mol) of CoCl₂.6 H₂ O. The mixture is cooled,then extracted with ethyl ether; the organic phase is separated; and thesolvent is removed in vacuo. The residue is taken up in 3 L of water andtreated with 16.8 g (0.1 mol) of cesium chloride to give, on cooling,46.3 g (0.07 mol, 80%) of Cs{[1-(n--C₈ H₁₇)-1,2-B₉ C₂ H₁₀ ]₂ Co}.

Example 3 Cesium Bis[6-(p-fluorophenyl)-1,2-dicarbollyl]cobal(III)

3-(p-Fluorophenyl)-1,2-dicarba-closo-dodecaborane(12) is prepared by theprocedure described by Adler and Hawthorne in "Determination of theElectronic Properties of Carboranes, Carborane Anions, andMetallocarboranes from Fluorine-19 Nuclear Magnetic Resonance Studies,"J. Amer. Chem. Soc. 92:6174 (1970), which is incorporated herein byreference. Degradation of3-(p-fluorophenyl)-1,2-dicarba-closo-dodecaborane(12) to6-(p-fluorophenyl)-1,2-dicarbadodecahydroundecaborate(-1) ion andsubsequent conversion tobis[6-(p-fluorophenyl)-1,2-dicarbollyl]cobal(III) ion is done usingprocedures developed for the non-fluorinated analogs. See M. Hawthorneand P. Wegner, "The Reconstruction of the1,2-Dicarbaclovododecaborane(12) Structure by Boron-Atom Insertion with1,2-Dicarbollide Ions", J. Amer. Chem. Soc. 90:896 (1968), which isincorporated by reference herein.

Thus, a solution of 5.0 g (89 mmol) of potassium hydroxide in 75 mL ofabsolute ethanol is placed in a 300 mL three-necked flask equipped witha mechanical stirrer and a nitrogen inlet topped reflux condenser. Asolution of 3-(p-fluorophenyl)-1,2-dicarba-closo-dodecaborane(12) (5.0g, 21 mmol) in 50 mL of absolute ethanol is added to the flask, and theresulting solution is heated at the reflux temperature for 10 hours. Theethanol is removed using a rotary evaporator. The white solid residue isdissolved in the minimum mount of 6M hydrochloric acid and filteredthrough Celitc. The Celitc cake is washed with two 15 mL portions ofwater. The combined washings and filtrate are treated with a 50%solution of trimethylammonium chloride. The precipitate is separated byfiltration and recrystallized from ethanol-water to yield 5.2 g (18mmol, 86%) of [(CH₃)₃ NH][6-(p-FC₆ H₄)-1,2-B₉ C₂ H₁₁ ].

A 500 mL, three-necked flask equipped with a nitrogen inlet toppedreflux condenser, pressure equalized dropping funnel and a magneticstirring bar is charged with sodium hydride (1.5 g of a 56% dispersionin mineral oil, 0.84 g, 35 mmol). The oil is removed by washing thesodium hydride with two 20 mL portions of dry tetrahydrofuran. Freshtetrahydrofuran (50 mL) is added to the flask, and tetrahydrofuran (50mL) containing [(CH₃)₃ NH][6-(p-FC₆ H₄)-1,2-B₉ C₂ H₁₁ ] (4.3 g, 15 mmol)is carefully added from the dropping funnel to the flask containing thesodium hydride slurry. After the addition is complete, the reactionmixture is heated at the reflux temperature for 3 hours. Trimethylamineis removed from the solvent by passing dry nitrogen over the solutionand out through the condenser during the last 30 minutes of the refluxperiod. The mixture is then allowed to cool, and the excess sodiumhydride is separated by filtration. The filtrate (containing 15 mmol of6-(p-fluorophenyl)-1,2-dicarbollide ion) is treated with atetrahydrofuran suspension of 1.6 g (12.0 mmol) of anhydrous cobaltchloride. The mixture is heated at the reflux temperature for 2 hoursunder nitrogen, cooled and filtered to remove the cobalt metal andsodium chloride formed. The solvent is evaporated and the residuedissolved in hot water. The solution is filtered and the yellow filtratetreated with excess cesium chloride. The precipitate is recrystallizedfrom aqueous ethanol to yield 2.5 g (3.9 mmol, 52%) of Cs{[6-(p-FC₆H₄)-1,2-B₉ C₂ H₁₀ ]₂ Co}.

Example 4 Cesium Bis[8-(iodo)-1,2-dicarbollyl]cobalt(III), and CesiumBis[8-(n-decyl)-1,2-dicarbollyl]cobalt(III)

A 500 mL flask equipped with a mechanical stirrer, a nitrogen inlettopped reflux condenser and a pressure equalized dropping funnel ischarged with a solution of K[(1,2-B₉ C₂ H₁₁)₂ Co](10.0 g, 28 mmol) in100 mL of absolute ethanol. Under a very slow stream of nitrogen andwith stirring, iodine (15.0 g, 59 mmol) dissolved in 50 mL of ethanol isadded over 1 hour. The contents of the flask are stirred at roomtemperature for an additional 3 hours then heated at the refluxtemperature for 2 hours. Excess iodine is reduced by addition of Na₂SO₃.7 H₂ O. The cooled mixture is filtered, then water (200 mL) is addedand the contents of the flask stirred for 30 minutes. Excess aqueouscesium chloride is added and the mixture is cooled to 0° C. Theprecipitate is isolated by filtration then recrystallized from hotaqueous ethanol to yield 17.3 g (24 mmol, 89%) of Cs{[8-(I)-1,2-B₉ C₂H₁₀ ]₂ Co}.

A 500 mL flask equipped with a mechanical stirrer, a nitrogen inlettopped reflux condenser and a pressure equalized dropping funnel ischarged with tetrahydrofuran (100 mL) and Cs{[8-(I)-1,2-B₉ C₂ H₁₀ ]₂ Co}(17.3 g, 24 mmol). Under a slow stream of nitrogen and with stirring, asolution of decylmagnesium bromide (100.0 mL, 1.0M, 100 mmol) is addedover 1 hour. Catalytic amounts of (Ph₃ P)₂ PdCl₂ (250 mg) and CuI (75mg) are added. The mixture is heated at the reflux temperature for 48hours, cooled, then filtered. Water (2 mL) is added and the mixturestirred for 15 minutes, then the solvent is removed on a rotaryevaporator. The semi-solid residue is dissolved in acetone, the mixtureis filtered, and water is added. The precipitate is recrystallized fromaqueous acetone to yield Cs{[8-(n--C₁₀ H₂₁)-1,2-B₉ C₂ H₁₀ ]₂ Co} (13.6g, 19 mmol, 76%).

Example 5 Cesium Bis[8-(hydroxy)-1,2-dicarbollyl]cobalt(III), and CesiumBis[8-(tetramethyiphenyldisiloxy)-1,2-dicarbollyl]cobalt(III)

Bis[8-(hydroxy)-1,2-dicarbollyl]cobalt(III) anion is prepared by themethod described in J. Francis and M. Hawthorne, "Synthesis andReactions of Novel Bridged Dicarbollide Complexes HavingElectron-Deficient Carbon Atoms", Inorg. Chem. 10:594 (1971), which isincorporated by reference herein. Thus, K[(1,2-B₉ C₂ H₁₁)₂ Co] (30.6 g,84 mmol) is dissolved in 300 mL of a 4:1 mixture of icetic acid-aceticanhydride 0.05N in HClO₄ and heated at 100° C. for 24 hours. Thesolution is cooled, the orange solid is collected, washed with aceticacid, and recrystallized from benzene-heptane to give golden yellowcrystals of K[(1,2-B₉ C₂ H₁₀)₂ CoO₂ CCH₃ ] (22.2 g, 52.9 mmol, 63%). TheK[(1,2-B₉ C₂ H₁₀)₂ CoO₂ CCH₃ ] is dissolved in 4:1 ethanol-water 0.1N inHCl and heated to reflux for 1 hour under nitrogen. Two volumes of waterand one volume of saturated NaCl solution are added, and the product isprecipitated with CsCl. The solid product is recrystallized fromacetone-toluene and dried at 140° C. in vacuo to yield 25.8 g (52.8mmol) of Cs{[8-(OH)-1,2-B₉ C₂ H₁₀ ]₂ Co}.

A 500 mL three-neck flask fitted with a mechanical stirrer and anitrogen inlet topped reflux condenser is cooled in an ice bath thencharged with 20.0 g (41 mmol) of Cs{[8-(OH)-1,2-B₉ C₂ H₁₀ ]₂ Co} and20.8 g (85 mmol) of chlorotetramethylphenyldisiloxane. The mixture isstirred under nitrogen for 1 hour, then the ice bath is removed andstirring continued while the mixture is warmed. Finally, the stirredmixture is heated to 50° C. until hydrogen chloride evolution ceases.Excess chlorotetramethylphenyldisiloxane is removed by subjecting themixture to vacuum to yield (38.0 g, 42 mmol) of Cs{[1,2-B₉ C₂ H₁₀OSi(CH₃)₂ OSi(CH₃)₂ (C₆ H₅)]₂ Co }.

Example 6 Cesium Bis[9,10-(sec--C₄ H₉)₂ -1,7-dicarbollyl]cobalt(III)

A 1000 mL flask equipped with mechanical stirring, thermocouple and anitrogen inlet-topped reflux condenser is charged with 45.6 g (0.10 mol)of Cs[bis-(1,7-B₉ C₂ H₁₁)₂ Co] and 450 g (515 mL, 4.7 mol) of sec--ClC₄H₉. Stirring is started and anhydrous aluminum chloride, 1.3 g (0.01mol) is added. The mixture is stirred with sufficient cooling tomaintain the temperature at near ambient for 3 hours. The mixture isfiltered and excess 2--ClC₄ H₉ strippd using a rotary evaporator toyield Cs{[9,10-(sec--C₄ H₉)₂ -1,7-B₉ C₂ H₇ ]₂ Co} (63.3 g, 0.07 mol) asa viscous oil.

Example 7 Cesium 1--CH₂ CHCH₂ CH₂ -1,2-B₉ C₂ H₁₁, Cesium {[1--CH₂ CHCH₂CH₂ -1,2-B₉ C₂ H₁₀ ]Co[1--CH₃ -1,2-B₉ C₂ H₁₀ ]}, and Cesium {[1--CH₂CHCH₂ CH₂ -1,2-B₉ C₂ H₁₀ ]Co[1--CH₃ -1,2-B₉ C₂ H₁₀ ]}SubstitutedSilicone Oil

The preparation of 1--CH₃ -1,2-B₁₀ C₂ H₁₁, 1-BrCH₂ -B₁₀ C₂ H₁₁ and theGrignard reagent (1-BrMgCH₂ -B₁₀ C₂ H₁₁) are accomplished by the methodsdescribed in Hawthorne et at., "Icosahedral Carboranes and IntermediatesLeading to the Preparation of Carbametallic Boron Hydride Derivatives",Inorganic Synthesis 10:91 (1967), which is incorporated by referenceherein. The Grignard reagent in ethyl ether solution is treated withallyl bromide (CH₂ CHCH₂ Br) to yield 1--CH₂ CHCH₂ CH₂ -1,2-B₁₀ C₂ H₁₁using an adaptation of the literature method. The degradation of 1--CH₃-1,2-B₁₀ C₂ H₁₁ and 1--CH₂ CHCH₂ CH₂ -1,2-B₁₀ C₂ H₁₁ to 1--CH₃ -1,2-B₉C₂ H₁₁ ion and 1--CH₂ CHCH₂ CH₂ -1,2-B₉ C₂ H₁₁ ion respectively isaccomplished by the methods described in Hawthome etal., "Pi-DicarbollylDerivatives of the Transition Metals. Metallocene Analogs", J. Amer.Chem. Soc. 90:879 (1968), the disclosure of which is incorporated byreference herein.

A solution of [(CH₃)₃ NH][1--CH₂ CHCH₂ CH₂ -1,2-B₉ C₂ H₁₁ ] (9.89 g, 40mmol) and [(CH₃)₃ NH][1--CH₃ -1,2-B₉ C₂ H₁₁ ] (8.29 g, 40 mmol) intetrahydrofuran (300 mL) is treated with excess NaH (7.56 g, 170 mmol,54% in mineral oil), then filtered under nitrogen: The resultingsolution of Na[1--CH₂ CHCH₂ CH₂ -1,2-B₉ C₂ H₁₀ ] and Na[1--CH₃ -1,2-B₉C₂ H₁₀ ] is added to a slurry of anhydrous cobalt chloride (8.44 g, 65mmol) in tetrahydrofuran. The mixture is heated to the refluxtemperature and maintained for 2 hours, then cooled and filtered. Thesolvent is evaporated using a rotary evaporator. The solid is extractedwith hot water, then filtered. Excess cesium chloride is added and theprecipitate is dissolved in boiling acetone, filtered, and sufficientwater is added to just initiate cloudiness. The solution is allowed tocool, during which time crystals of Cs{[1--CH₂ CHCH₂ CH₂ -1,2-B₉ C₂ H₁₀][Co(III)][1--CH₃ -1,2-B₉ C₂ H₁₀ ]} form (9.38 g, 17.9 mmol, 44.8%).

A 500 mL flask equipped with a mechanical stirrer is charged withpolydimethylsiloxane containing terminal SiH groups, H--Si(CH₃)₂--O--[Si(CH₃)₂ -O]_(n) --Si(CH₂)-H (140 g, 8 mmol, n≈234) (availablefrom United Chemical Technologies, Inc., Bristol, Pa.). The flask isheated to 40° C. with stirring then 8.39 g (16 mmol) of Cs{[1--CH₂ CHCH₂CH₂ -1,2-B₉ C₂ H₁₀ ][Co(III)][1--CH₃ -1,2-B₉ C₂ H₁₀ ]} and a platinumcatalyst (chloroplatinic acid) are added in small portions over 1 hour.The mixture is heated and stirred at 90° C. for 2 hours. The resultantsilicone, Cs{[1--CH₃ -1,2-B₉ C₂ H₁₀ ][Co(III)][1--CH₂ CH₂ CH₂ CH₂-1,2-B₉ C₂ H₁₀ ]--Si(CH₃)₂ --O--[Si(CH₃)₂ -O]_(n) --Si(CH₂)--Cs{[1--CH₂CH₂ CH₂ CH₂ -1,2-B₉ C₂ H₁₀ ][Co(III)][1--CH₃ -1,2-B₉ C₂ H₁₀ ]}(n≈234),end-capped with transition metal dicarbollide ion moieties, is isolated.Depending on the value of n and the composition of the silicone used,the polymer resulting from such reactions is a liquid (oil) or anelastomer.

Example 8 Cesium [8-Iodo-1,2-dicarboilyl]Co[1,2-dicarbollyl], Cesium[8-vinyl-1,2-dicarbollyl]Co[1,2-dicarbollyl], and CesiumBis[1,2-dicarbollyl]cobalt(III) Substituted Silicone Oil

A 500 mL flask equipped with a mechanical stirrer, a nitrogen inlettopped reflux condenser and a pressure equalized dropping funnel ischarged with a solution of K[(1,2-B₉ C₂ H₁₁)₂ Co] (10.0 g, 28 mmol) in100 mL of absolute ethanol. The solution is cooled to 0° C. Under a veryslow stream of nitrogen and with stirring, iodine (6.9 g, 27 mmol)dissolved in 20 mL of ethanol is added over 1 hour. The flask is allowedto warm to ambient temperature over 3 hours and then stirred at roomtemperature for an additional 3 hours. The mixture is filtered, thenwater (200 mL) is added and the contents of the flask stirred for 30minutes. Excess aqueous cesium chloride is added and the mixture iscooled to 0° C. The precipitate is isolated by filtration thenrecrystallized from hot aqueous ethanol to yield 14.5 g (25 mmol, 89%)of Cs[(8-(I)-1,2-B₉ C₂ H₁₀)Co(1,2-B₉ C₂ H₁₁)].

A 500 mL flask equipped with a mechanical stirrer, a nitrogen inlettopped reflux condenser and a pressure equalized dropping funnel ischarged with tetrahydrofuran (100 mL) and Cs[(8-(I)-1,2-B₉ C₂H₁₀)Co(1,2-B₉ C₂ H₁₁)] (14.5 g, 25 mmol). Under a slow stream ofnitrogen and with stirring, a solution of vinylmagnesium bromide (50.0mL, 1.0M, 50 mmol) is added over 1 hour. Catalytic mounts of (Ph₃ P)₂PdCl₂ (250 mg) and CuI (75 mg) are added. The mixture is heated at thereflux temperature for 48 hours, cooled then filtered. Water (1 mL) isadded and the mixture stirred for 15 minutes, then the solvent isremoved on a rotary evaporator. The semi-solid residue is dissolved inacetone, the mixture filtered, and water is added. The precipitate isrecrystallized from aqueous acetone to yield Cs{[8-(C₂ H₃)-1,2-B₉ C₂ H₁₀]Co[1,2-B₉ C₂ H₁₁ ]} (9.1 g 19 mmol, 76%).

A 500 mL flask equipped with a mechanical stirrer is charged with apolydimethylsiloxane containing SiH groups, Si(CH₃)₃ --O--[Si(CH₃)₂--O--SiH(CH₃ )--O--Si(CH₃)₂ --O--]₄ --Si(CH₃)₃ (4.0 g, 4 mmol). Theflask is heated to 40° C. with stirring, then 7.7 g (16 mmol) ofCs{[8-(C2H3)-1,2-B₉ C₂ H₁₀ ]Co[1,2-B₉ C₂ H₁₁ ]} and a platinum catalyst(chloroplatinic acid) are added in small portions over 1 hour. Themixture is heated and stirred at 90° C. for 2 hours. The resultingsilicone, Si(CH₃)₃ --O--[Si(CH₃)₂ --O--Si{Cs[(-8--C₂ H₄ -1,2-B₉ C₂H₁₀)Co(1,2-B₉ C₂ H₁₁)]}(CH₃)--O--Si(CH₃)₂ --O--]₄ --Si(CH₃)₃ containingtransition metal dicarbollide ion moieties, is isolated. Depending onthe molecular weight and composition of the silicone used, the polymerresulting from such reactions is a liquid or an elastomer.

Example 9 Immobilization of the Liquid Membrane in a Support Polymer

A round bottom flask is charged with a solution of cesiumbis[1,2-dicarbollyl]cobalt(III) anion substituted silicone oil (fromExample 8) in o-dichlorobenzene. A microporous support polymer (Accurelpolypropylene film) is placed in the flask, which is then cooled to 0°C. and evacuated. The flask is closed (under vacuum) and allowed to warmto ambient temperature. After standing for 1 hour, the support polymeris removed from the solution and exposed to vacuum to remove solvent,leaving the pores of the polymeric support filled withbis[1,2-dicarbollyl]cobalt(III) anion substituted silicone.

Example 10 Extraction of Cs⁺ From Aqueous Solution Using the ConjugateAcid of Bis[1-(n-octyl)-1,2-dicarbollyl]cobalt(III) Anion in Xylene

The hydrogen form (conjugate acid) of [1-(n--C₈ H₁₇)-1,2-B₉ C₂ H₁₀ ]₂Co⁻ may be obtained from the cesium salt by use of an ion-exchange resinor by treatment with aqueous acid followed by extraction with organicsolvent. Thus, in a 1000 mL separatory funnel, a slurry of Cs{[1-(n--C₈H₁₇)-1,2-B₉ C₂ H₁₀ ]₂ Co} (from Example 2) (4.08 g, 6.0 mmol) in 300 gof 3M HNO₃ is extracted with 300 g of xylene. The organic layer isseparated and washed with 300 g of fresh 3M HNO₃ solution. The resultingxylene solution of H{[1-(n--C₈ H₁₇)-1,2-B₉ C₂ H₁₀ ]₂ Co} is added to a1000 mL flask equipped with a magnetic stirring bar. An aqueous solution(300 mL), 3M in nitric acid and containing 0.58 g (3.0 mmol) of cesiumnitrate, is added to the flask (≈0.01M in Cs⁺, the approximateconcentration found in actual nuclear waste). The flask is heated to andmaintained at 55° C. with stirring for 1 hour. Stirring is stopped, theorganic layer separated and treated with 300 g of 3M nitric acid at 55°C., with stirring for 1 hour. The aqueous phase is separated and shownto contain 2.5 mmol of cesium by atomic emission spectroscopy.

Example 11 Extraction of Cs⁺ From Aqueous Solution Using the ConjugateAcid of Bis[8-(tetramethylphenyldisiloxy)-1,2-dicarbollyl]cobalt(III)Anion in Silicone Oil

A 1000 mL flask equipped with a magnetic stirring bar is charged with3.4 g (6.0 mmol) of Cs{[B₉ C₂ H₁₀ OSi(CH₃)₂ OSi(CH₃)₂ (C₆ H₅)]₂ Co}(from Example 5) and 300 g of silicone oil (Dow-Corning 704). A solution3M in nitric acid is added and the flask heated to 55° C. with stirring.After 1 hour, the silicone oil phase is separated and washed with 300 gof 3M nitric acid solution. The silicone oil phase is separated andtreated with 300 mL of an aqueous solution, 3M in nitric acid andcontaining 0.58 g (3.0 mmol) of cesium nitrate at 55° C., with stirringfor 1 hour. The aqueous phase is separated and the silicone oil phase istreated with 300 g of 3M nitric acid at 55° C., with stirring for 1hour. The aqueous phase is separated and shown to contain 2.4 mmol ofcesium by atomic emission spectroscopy.

Example 12 Extraction of Cs⁺ From Aqueous Solution Using the ConjugateAcid of Bis[1,2-dicarbollyl]Cobalt(III) Anion SubstitutedPolydimethylsiloxane

A 1000 mL flask equipped with a magnetic stirring bar is charged with4.40 g (1.5 mmol, 4 meq of transition metal dicarbollide complex permmol of silicone) of bis[1,2-dicarbollyl]cobalt(III) union substitutedsilicone oil (from Example 8). A 3M in nitric acid solution (300 g) isadded and the flask heated to 55° C. with stirring. After 1 hour thesiloxane-dicarbollide oil phase is separated and washed with 300 g of 3Mnitric acid solution. The siloxane-dicarbollide oil phase is separatedand treated with 300 g of an aqueous solution, 3M in nitric acid andcontaining 0.58 g (3.0 mmol) of cesium nitrate, at 55° C. with stirringfor 1 hour. The aqueous phase is separated and the siloxane-dicarbollideoil phase is treated with 300 g of 3M nitric acid with stirring at 55°C. for 1 hour. The aqueous phase is separated and shown to contain 2.1mmol of cesium by atomic emission spectroscopy.

Example 13 Extraction of Sr⁺² From Aqueous Solution Using the ConjugateAcid of Bis[1,2-dicarbollyl]cobalt(III) Anion SubstitutedPolydimethylsiloxane With PEG-400 Additive

A 1000 mL flask equipped with a magnetic stirring bar is charged with4.40 g (1.5 mmol) of bis[1,2-dicarbollyl]cobalt(III) union substitutedsilicone oil (from Example 8). A solution 3M in nitric acid is added andthe flask heated to 55° C. with stirring. After 1 hour thesiloxane-dicarbollide oil phase is separated and washed with 300 g of 3Mnitric acid solution. The siloxane-dicarbollide oil phase is separatedand treated with an aqueous solution, 3M in nitric acid, containing 4.00g, 10.0 mmol of PEG-400 and 0.63 g (3.0 mmol) of strontium nitrate at55° C. with stirring for 1 hour. The aqueous phase is separated and thesiloxane-dicarbollide oil phase is treated with 300 g of 3M nitric acidwith stirring at 55° C. for 1 hour. The aqueous phase is separated andcontains 2.3 mmol of strontium.

Example 14 Extraction of CS⁺ From Aqueous Solution Using the ConjugateAcid of Bis[1,2-dicarbollyl]cobalt(III) Anion Substituted Silicone OilImmobilized in Polypropylene Film

The two compartments of an H-cell are each equipped with a magneticstirring bar and are separated by an Accurel film (5.0 cm diameter)containing immobilized bis[1,2-dicarbollyl]cobalt(III) anion substitutedsilicone oil (from Example 9). Both compartments are charged with asolution 3M in nitric acid to cover the membrane and the cell is heatedto 55° C. with stirring. After 48 hours, the cell is emptied, and onecompartment (A) is charged with 300 g of an aqueous solution, 3M innitric acid and containing 0.58 g (3.0 mmol) of cesium nitrate. Theother compartment (B) is charged with 300 g of 3M HCl. After 48 hours ofstirring at 55° C., the solution in compartment (B) is collected and canbe shown by atomic emission spectroscopy to contain 7.2×10⁻¹ mmol ofcesium.

What is claimed is:
 1. A substituted dicarbollide comprising a compoundselected from the group consisting of:a) a metal dicarbollide ion of theformula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1).sub.2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si--O--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[Si(R"')(R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3 ;

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2 ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, --Si(R')₂ (C₆ H₅) or R"', k is 1 to 10, and R',R", R"', b, c and d are as defined above; and R₂ is selected from thegroup consisting of chlorine, bromine, methyl and trifluoromethyl;provided that at least one R must be R₁.
 2. A substituted metaldicarbollide ion as recited in claim 1, wherein a is 0 and R is alkylhaving from 7 to 10 carbon atoms.
 3. A substituted metal dicarbollideion as recited in claim 1, wherein R is fluoro- substituted alkyl havingfrom 2 to about 10 carbon atoms.
 4. A substituted metal dicarbollide ionas recited in claim 1, wherein K is substituted phenyl selected from thegroup consisting of 1-o-fluorophenyl, biphenyl, phenylfluorophenyl andsubstituted phenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl.
 5. A substituted metal dicarbollide ion as recited in claim 1,wherein R is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, --Si(R')₂ (C₆ H₅) or R"', b is 0 to 10, c is 0 or1, d is 0 to 10, kis 1 to 10, R' is methyl or trifluoromethyl, R" isphenyl or fluoro- substituted phenyl, R"' is a metal dicarbollide ionmoiety of the formula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2 ]

where a is 0 to 3, W is oxygen or alkylene having from 2 to about 10carbon atoms, and each Z is independently selected from hydrogen, alkylhaving from about 1 to about 10 carbon atoms; fluoro- substituted alkylhaving from 1 to about 10 carbon atoms; phenyl or substituted phenyl ofthe formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl.
 6. A metal dicarbollide ion-substituted organosiloxane of claim1 having the formula:

    (R').sub.3 Si--O--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[Si(R"')(R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3 ;

R' is methyl or trifluoromethyl; R" is phenyl or fluoro- substitutedphenyl; R"' is a metal dicarbollide ion moiety of the formula:

    W-[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2 ]

wherein a is 0 to 3; M is a transition metal capable of forming atrivalent oxidation state; W is oxygen or alkylene having from 2 toabout 10 carbon atoms, and each Z is independently selected fromhydrogen; alkyl having from 1 to about 10 carbon atoms; fluoro-substituted alkyl having from 1 to about 10 carbon atoms; phenyl orsubstituted phenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; b, d, f, and h are 0 to 10; c and g are 0 or 1; and e and i are1 to
 10. 7. A substituted metal dicarbollide ion as recited in claim 1,wherein M is selected from the group consisting of iron, cobalt andchromium.
 8. A substituted metal dicarbollide ion as recited in claim 7,wherein M is cobalt.
 9. The conjugate acid of a substituteddicarbollide; wherein the substituted dicarbollide comprises:a) a metaldicarbollide ion of the formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1).sub.2 ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si-O{[Si (R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.4 -[SiR"') (R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2.sup.- ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and q are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅) or R"', k is 1 to 10, and R', R",R"', b, c and d are defined as above; and R₂ is selected form the groupconsisting of chlorine, bromine, methyl and trifluoromethyl; providedthat at least one R must be R₁.
 10. An extraction agent comprising anorganosiloxane having at least one metal dicarbollide ion moiety boundthereto.
 11. An extraction agent as recited in claim 10, wherein theorganosiloxane comprises a metal dicarbollide ion-substitutedorganosiloxane of the formula:

    (R').sub.3 Si--O--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[Si(R"')(R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }Si(R').sub.3 ;

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2.sup.- ]

wherein M is a transition metal capable of forming a trivalent oxidationstate; W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    C.sub.6 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, --Si(R')₂ (C₆ H₅) or R"', k is 1 to 10, and R',R", R"', b, c and d are as defined above; and R₂ is selected from thegroup consisting of chlorine, bromine, methyl and trifluoromethyl;provided that at least one R must be R₁.
 12. An extraction agent asrecited in claim 11, wherein the at least one metal dicarbollide ionmoiety contains a metal selected from the group consisting of iron,cobalt and chromium.
 13. An extraction agent as recited in claim 12,wherein the at least one metal dicarbollide ion moiety comprises cobalt.14. An extraction agent as recited in claim 11, selected from the groupconsisting of bis[1-(n-hexyl)-dicarbollyl]metal anion substitutedsilicone, bis[1-(n-heptl)-dicarbollyl]metal anion substituted silicone,bis[1-(n-octyl)-dicarbollyl]metal anion substituted silicone,bis[1-(n-nonyl)-dicarbollyl]metal anion substituted silicone, andbis[1-(n-decyl)-dicarbollyl]metal anion substituted silicone.
 15. Amethod for selectively extracting cesium ions from an aqueous phase,comprising:forming an aqueous-nonaqueous liquid combination bycontacting a pregnant aqueous phase containing cesium ions with a firstnonaqueous phase comprising at least one extraction agent, wherein theextraction agent is a substituted dicarbollide; and separating theliquid combination into a stripped aqueous phase and a pregnantnonaqueous phase, wherein the pregnant nonaqueous phase contains cesiumions extracted from the pregnant aqueous phase;wherein the substituteddicarbollide comprises: a) a metal dicarbollide ion of the formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1)2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si-O{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[SiR"')(R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2 ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--]d}.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅) or R"', k is 1 to 10, and R', R",R"', b, c and d are defined as above; and R₂ is selected form the groupconsisting of chlorine, bromine, methyl and trifluoromethyl; providedthat at least one R must be R₁.
 16. The method of claim 15 wherein thefirst nonaqueous phase comprises from about 0.005M to about 0.5M of theextraction agent.
 17. The method of claim 15 wherein the extractionagent is an alkyl- or phenyl-substituted metal dicarbollide ion andwherein the first nonaqueous phase further comprises a hydrocarbonsolvent.
 18. The method of claim 15 wherein the extraction agent is analkyl- or phenyl-substituted metal dicarbollide ion and wherein thefirst nonaqueous phase further comprises kerosene, xylene, 1-octanol,and tributylphosphate.
 19. The method of claim 15 wherein the extractionagent is a fluorinated alkyl, or phenyl-substituted metal dicarbollideand wherein the first nonaqueous phase further comprises a fluorinatedhydrocarbon solvent.
 20. The method of claim 19 wherein the fluorinatedhydrocarbon solvent is fluorinated kerosene, a fluorinated biphenylcompound or a fluorinated polyether.
 21. The method of claim 15 whereinthe extraction agent is a an organosiloxane-substituted metaldicarbollide ion and wherein the first nonaqueous phase furthercomprises a silicone oil.
 22. A method as recited in claim 15, whichfurther comprises the step of stripping cesium ions from the pregnantnonaqueous phase.
 23. A method as recited in claim 22, wherein thecesium ions are stripped from the pregnant nonaqueous phase by treatmentwith mineral acid.
 24. A method for selectively extracting strontiumions from a substantially cesium-free aqueous solution,comprising:adding a polyethylene glycol pr p-nonylphenyl-nonaethyleneglycol to a pregnant aqueous phase containing strontium ions; forming anaqueous-nonaqueous liquid combination by contacting the pregnant aqueousphase with a first nonaqueous phase comprising at least one extractionagent, wherein the extraction agent is a substituted dicarbollide; andseparating the liquid combination into a stripped aqueous phase and apregnant nonaqueous phase, wherein the pregnant nonaqueous phasecontains strontium ions extracted from the pregnant aqueousphase;wherein the substituted dicarbollide comprises: a) a metaldicarbollide ion of the formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1).sub.2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si-O{[Si(R').sub.2 --O--].sub.d -[SiR"'--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2 ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where i is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and q are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅) or R"', k is 1 to 10, and R', R",R"', b, c and d are defined as above; and R₂ is selected form the groupconsisting of chlorine, bromine, methyl and trifluoromethyl; providedthat at least one R must be R₁.
 25. The method of claim 24 wherein thefirst nonaqueous phase comprises from about 0.005M to about 0.5M of theextraction agent.
 26. The method of claim 24 wherein the extractionagent is an alkyl- or phenyl-substituted metal dicarbollide ion andwherein the first nonaqueous phase further comprises a hydrocarbonsolvent.
 27. The method of claim 24 wherein the extraction agent is analkyl- or phenyl-substituted metal dicarbollide ion and wherein thefirst nonaqueous phase further comprises kerosene, xylene, 1-octanol,and tributylphosphate.
 28. The method of claim 24 wherein the extractionagent is a fluorinated alkyl- or phenyl-substituted metal dicarbollideand wherein the first nonaqueous phase further comprises a fluorinatedhydrocarbon solvent.
 29. The method of claim 28 wherein the fluoronatedhydrocarbon solvent is fluorinated kerosene, a fluorinated biphenylcompound or a fluorinated polyether.
 30. The method of claim 24 whereinthe extraction agent is a an organosiloxane-substituted metaldicarbollide ion and wherein the first nonaqueous phase furthercomprises a silicone oil.
 31. A method as recited in claim 24, whichfurther comprises the step of stripping strontium ions from the pregnantnonaqueous phase.
 32. A method as recited in claim 31, wherein thestrontium ions are stripped from the pregnant nonaqueous phase bytreatment with mineral acid.
 33. A method for selectively extractingcesium and strontium ions from an aqueous solution, comprising:formingan aqueous-nonaqueous liquid combination by contacting the pregnantaqueous phase containing cesium and strontium ions with a firstnonaqueous phase comprising at least one extraction agent, wherein theextraction agent is a substituted dicarbollide; and separating theliquid combination into a stripped aqueous phase and a pregnantnonaqueous phase, wherein the pregnant nonaqueous phase contains cesiumions extracted from the pregnant aqueous phase; modifying the strippedaqueous phase by adding a polyethylene glycol orp-nonylphenylnonaethylene glycol; forming a second aqueous-nonagueousliquid combination by contacting the modified, stripped aqueous phasewith a fresh nonaqueous phase comprising at least one extraction agent,wherein the extraction agent is a substituted dicarbollide; separatingthe second liquid combination into a stripped aqueous phase and a secondpregnant nonaqueous phase, wherein the second pregnant nonaqueous phase,wherein the second pregnant nonaqueous phase contains strontiumions;wherein the substituted dicarbollide comprises: a) a metaldicarbollide ion of the formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1)2; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si-O{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[SiR"') (R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-1 R.sub.a Z).sub.2 ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and q are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅) or R"', k is 1 to 10, and R', R",R"', b, c and d are defined as above; and R₂ is selected form the groupconsisting of chlorine, bromine, methyl and trifluoromethyl; providedthat at least one R must be R₁.
 34. A method for extracting cesium ionsfrom an aqueous solution, comprising contacting the cesium ions with atleast on extraction agent comprising a substituted dicarbollide; whereinthe substituted dicarbollide comprises:a) a metal dicarbollide ion ofthe formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1)2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:.

    (R').sub.3 Si-0{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[SiR"') (R')--O--].sub.e [Si(R').sub.2 --O--].sub.f [SiR'R"'--O--].sub.g [Si(R').sub.2--O--].sub.h }.sub.j Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2.sup.- ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅ H) or R"', k is 1 to 10, and R',R", R"', b, c and d are defined as above; and R₂ is selected form thegroup consisting of chlorine, bromine, methyl and trifluoromethyl;provided that at least one R must be R₁.
 35. A method as recited inclaim 34 wherein the cesium ions are contacted with the extraction agentby passing the aqueous solution through a semipermeable membrane or amicroporous polymer film that comprises the extraction agent.
 36. Amethod as recited in claim 35, wherein, prior to extraction, themembrane is treated with mineral acid.
 37. A method for extractingstrontium ions from an aqueous solution, comprising contacting thestrontium ions, in the presence of polyethylene glycol orp-nonylphenylnonaethylene glycol, with at least one extraction agentcomprising a substituted dicarbollide; wherein the substituteddicarbollide comprises:a) a metal dicarbollide ion of the formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1)2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si-O{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[SiR"') (R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"'is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.z Z).sub.2 ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alkyl having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to S, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to S, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m- fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅) or R"', k is 1 to 10, and R', R",R"', b, c and d are defined as above; and R₂ is selected form the groupconsisting of chlorine, bromine, methyl and trifluoromethyl; providedthat at least one R must be R₁.
 38. A method as recited in claim 37wherein the strontium ions are contacted with the extraction agent bypassing the aqueous solution through a semipermeable membrane. or amicroporous polymer film that comprises the extraction agent.
 39. Amethod as recited in claim 38, wherein, prior to extraction, themembrane is treated with mineral acid.
 40. A semipermeable membrane,comprising a silicone elastomer or microporous polymer film wherein theelastomer of film comprises at least one substituted dicarbollide:wherein the substituted dicarbollide comprises:a) a metal dicarbollideion of the formula:

    M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a+1)2.sup.- ; or

b) a metal dicarbollide ion-substituted organosiloxane of the formula:

    (R').sub.3 Si-O{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d -[SiR"') (R')--O--].sub.e -[Si(R').sub.2 --O--].sub.f [SiR'R"--O--].sub.g [Si(R').sub.2 --O--].sub.h }.sub.i Si(R').sub.3

wherein M is a transition metal capable of forming a trivalent oxidationstate; R' is methyl or trifluoromethyl; R" is phenyl or fluoro-substituted phenyl; R"' is a metal dicarbollide ion moiety of theformula:

    --W--[M(B.sub.9 C.sub.2 H.sub.10-a R.sub.a Z).sub.2.sup.- ]

where W is oxygen or alkylene having from 2 to about 10 carbon atoms,and each Z is independently selected from hydrogen, alkyl having fromabout 1 to about 10 carbon atoms; fluoro- substituted alky1 having from1 to about 10 carbon atoms; phenyl or substituted phenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl; a is 0 to 3; b, d, f, and h are 0 to 10; c and g are 0 or 1; ande and i are 1 to 10; and each R is independently selected from R₁ or R₂,where R₁ is alkyl having from about 7 to about 10 carbon atoms; fluoro-substituted alkyl having from 2 to about 10 carbon atoms; substitutedphenyl of the formula:

    --C.sub.5 H.sub.5-j Y.sub.j

where j is 1 to 5, and Y is fluorine, phenyl or fluoro- substitutedphenyl, with the proviso that R₁ cannot be 1-m-fluorophenyl or1-p-fluorophenyl; or R₁ is an organosiloxane of the formula:

    --W--{[Si(R').sub.2 --O--].sub.b [SiR'R"--O--].sub.c [Si(R').sub.2 --O--].sub.d }.sub.k E

where E is --Si(R')₃, Si(R')₂ (C₂ H₅) or R"', k is 1 to 10, and R', R",R"', b, c and d are defined as above; and R₂ is selected form the groupconsisting of chlorine, bromine, methyl and trifluoromethyl; providedthat at least one R must be R₁.
 41. A semipermeable membrane as recitedin claim 40, wherein the semipermeable membrane comprises a siliconeelastomer comprising an organosiloxane.
 42. A semipermeable membrane asrecited in claim 40, wherein the semipermeable membrane comprises apolypropylene polymer film.